diff --git a/sql/swad.sql b/sql/swad.sql
index 21204055..227d9e50 100644
--- a/sql/swad.sql
+++ b/sql/swad.sql
@@ -7,6 +7,7 @@ CREATE TABLE IF NOT EXISTS IP_prefs (
 	IP CHAR(15) NOT NULL,
 	UsrCod INT NOT NULL DEFAULT -1,
 	LastChange DATETIME NOT NULL,
+	FirstDayOfWeek TINYINT NOT NULL DEFAULT 0,
 	Layout TINYINT NOT NULL DEFAULT 0,
 	Theme CHAR(16) NOT NULL,
 	IconSet CHAR(16) NOT NULL,
@@ -1127,6 +1128,7 @@ CREATE TABLE IF NOT EXISTS usr_data (
 	Theme CHAR(16) NOT NULL,
 	IconSet CHAR(16) NOT NULL,
 	Language CHAR(2) NOT NULL,
+	FirstDayOfWeek TINYINT NOT NULL DEFAULT 0,
 	Photo CHAR(43) NOT NULL,
 	PhotoVisibility ENUM('user','course','system','world') NOT NULL DEFAULT 'user',
 	ProfileVisibility ENUM('user','course','system','world') NOT NULL DEFAULT 'user',
@@ -1154,6 +1156,7 @@ CREATE TABLE IF NOT EXISTS usr_data (
 	INDEX(Theme),
 	INDEX(IconSet),
 	INDEX(Language),
+	INDEX(FirstDayOfWeek),
 	INDEX(CtyCod),
 	INDEX(InsCtyCod),
 	INDEX(InsCod),
diff --git a/swad_account.c b/swad_account.c
index 40773e4b..f76bfaa6 100644
--- a/swad_account.c
+++ b/swad_account.c
@@ -29,6 +29,7 @@
 
 #include "swad_account.h"
 #include "swad_announcement.h"
+#include "swad_calendar.h"
 #include "swad_database.h"
 #include "swad_enrollment.h"
 #include "swad_global.h"
@@ -433,12 +434,12 @@ void Acc_CreateNewUsr (struct UsrData *UsrDat)
    /***** Insert new user in database *****/
    /* Insert user's data */
    sprintf (Query,"INSERT INTO usr_data (EncryptedUsrCod,Password,Surname1,Surname2,FirstName,Sex,"
-		  "Layout,Theme,IconSet,Language,PhotoVisibility,ProfileVisibility,"
+		  "Layout,Theme,IconSet,Language,FirstDayOfWeek,PhotoVisibility,ProfileVisibility,"
 		  "CtyCod,"
 		  "LocalAddress,LocalPhone,FamilyAddress,FamilyPhone,OriginPlace,Birthday,Comments,"
 		  "Menu,SideCols,NotifNtfEvents,EmailNtfEvents)"
 		  " VALUES ('%s','%s','%s','%s','%s','%s',"
-		  "'%u','%s','%s','%s','%s','%s',"
+		  "'%u','%s','%s','%s','%u','%s','%s',"
 		  "'%ld',"
 		  "'%s','%s','%s','%s','%s','%04u-%02u-%02u','%s',"
 		  "'%u','%u','-1','0')",
@@ -450,6 +451,7 @@ void Acc_CreateNewUsr (struct UsrData *UsrDat)
 	    The_ThemeId[UsrDat->Prefs.Theme],
 	    Ico_IconSetId[UsrDat->Prefs.IconSet],
 	    Txt_STR_LANG_ID[UsrDat->Prefs.Language],
+	    Cal_FIRST_DAY_OF_WEEK_DEFAULT,
             Pri_VisibilityDB[UsrDat->PhotoVisibility],
             Pri_VisibilityDB[UsrDat->ProfileVisibility],
 	    UsrDat->CtyCod,
diff --git a/swad_action.c b/swad_action.c
index 1c295324..76aa77f2 100644
--- a/swad_action.c
+++ b/swad_action.c
@@ -1273,6 +1273,7 @@ Profile:
        1078. ActChgThe			Change theme
        1079. ActReqChgLan		Ask if change language
        1080. ActChgLan			Change language
+-----> 1080. ActChg1stDay		Change first day of the week
        1081. ActChgCol			Change side columns
        1082. ActHidLftCol		Hide left side column
        1083. ActHidRgtCol		Hide right side column
@@ -2754,6 +2755,7 @@ struct Act_Actions Act_Actions[Act_NUM_ACTIONS] =
    /* ActChgThe		*/{ 841,-1,TabPrf,ActEdiPrf		,0x1FF,0x1FF,0x1FF,Act_CONTENT_NORM,Act_MAIN_WINDOW,The_ChangeTheme		,Pre_EditPrefs			,NULL},
    /* ActReqChgLan	*/{ 992,-1,TabPrf,ActEdiPrf		,0x1FF,0x1FF,0x1FF,Act_CONTENT_NORM,Act_MAIN_WINDOW,NULL			,Pre_AskChangeLanguage		,NULL},
    /* ActChgLan		*/{ 654,-1,TabPrf,ActEdiPrf		,0x1FF,0x1FF,0x1FF,Act_CONTENT_NORM,Act_MAIN_WINDOW,Pre_ChangeLanguage		,Pre_EditPrefs			,NULL},
+   /* ActChg1stDay	*/{1484,-1,TabPrf,ActEdiPrf		,0x1FF,0x1FF,0x1FF,Act_CONTENT_NORM,Act_MAIN_WINDOW,Cal_ChangeFirstDayOfWeek	,Pre_EditPrefs			,NULL},
    /* ActChgCol		*/{ 674,-1,TabPrf,ActEdiPrf		,0x1FF,0x1FF,0x1FF,Act_CONTENT_NORM,Act_MAIN_WINDOW,Pre_ChangeSideCols		,Pre_EditPrefs			,NULL},
    /* ActHidLftCol	*/{ 668,-1,TabPrf,ActEdiPrf		,0x1FF,0x1FF,0x1FF,Act_CONTENT_NORM,Act_MAIN_WINDOW,Pre_HideLeftCol		,Pre_EditPrefs			,NULL},
    /* ActHidRgtCol	*/{ 669,-1,TabPrf,ActEdiPrf		,0x1FF,0x1FF,0x1FF,Act_CONTENT_NORM,Act_MAIN_WINDOW,Pre_HideRightCol		,Pre_EditPrefs			,NULL},
@@ -4278,6 +4280,7 @@ Act_Action_t Act_FromActCodToAction[1+Act_MAX_ACTION_COD] =	// Do not reuse uniq
 	ActNewMaiOth,		// #1481
 	ActNewMaiStd,		// #1482
 	ActNewMaiTch,		// #1483
+	ActChg1stDay,		// #1484
 	};
 
 /*****************************************************************************/
diff --git a/swad_action.h b/swad_action.h
index fa37a709..68271533 100644
--- a/swad_action.h
+++ b/swad_action.h
@@ -70,9 +70,9 @@ typedef enum
 
 typedef int Act_Action_t;	// Must be a signed type, because -1 is used to indicate obsolete action
 
-#define Act_NUM_ACTIONS	(7+52+15+90+73+68+204+182+154+171+27+79)
+#define Act_NUM_ACTIONS	(7+52+15+90+73+68+204+182+154+171+27+80)
 
-#define Act_MAX_ACTION_COD 1483
+#define Act_MAX_ACTION_COD 1484
 
 #define Act_MAX_OPTIONS_IN_MENU_PER_TAB 20
 
@@ -1314,38 +1314,39 @@ typedef int Act_Action_t;	// Must be a signed type, because -1 is used to indica
 #define ActChgThe		(ActSeeAllStaCrs+47)
 #define ActReqChgLan		(ActSeeAllStaCrs+48)
 #define ActChgLan		(ActSeeAllStaCrs+49)
-#define ActChgCol		(ActSeeAllStaCrs+50)
-#define ActHidLftCol		(ActSeeAllStaCrs+51)
-#define ActHidRgtCol		(ActSeeAllStaCrs+52)
-#define ActShoLftCol		(ActSeeAllStaCrs+53)
-#define ActShoRgtCol		(ActSeeAllStaCrs+54)
-#define ActChgIco		(ActSeeAllStaCrs+55)
-#define ActChgMnu		(ActSeeAllStaCrs+56)
-#define ActChgNtfPrf		(ActSeeAllStaCrs+57)
+#define ActChg1stDay		(ActSeeAllStaCrs+50)
+#define ActChgCol		(ActSeeAllStaCrs+51)
+#define ActHidLftCol		(ActSeeAllStaCrs+52)
+#define ActHidRgtCol		(ActSeeAllStaCrs+53)
+#define ActShoLftCol		(ActSeeAllStaCrs+54)
+#define ActShoRgtCol		(ActSeeAllStaCrs+55)
+#define ActChgIco		(ActSeeAllStaCrs+56)
+#define ActChgMnu		(ActSeeAllStaCrs+57)
+#define ActChgNtfPrf		(ActSeeAllStaCrs+58)
 
-#define ActPrnUsrQR		(ActSeeAllStaCrs+58)
+#define ActPrnUsrQR		(ActSeeAllStaCrs+59)
 
-#define ActPrnMyTimTbl		(ActSeeAllStaCrs+59)
-#define ActEdiTut		(ActSeeAllStaCrs+60)
-#define ActChgTut		(ActSeeAllStaCrs+61)
-#define ActReqRemFilBrf		(ActSeeAllStaCrs+62)
-#define ActRemFilBrf		(ActSeeAllStaCrs+63)
-#define ActRemFolBrf		(ActSeeAllStaCrs+64)
-#define ActCopBrf		(ActSeeAllStaCrs+65)
-#define ActPasBrf		(ActSeeAllStaCrs+66)
-#define ActRemTreBrf		(ActSeeAllStaCrs+67)
-#define ActFrmCreBrf		(ActSeeAllStaCrs+68)
-#define ActCreFolBrf		(ActSeeAllStaCrs+69)
-#define ActCreLnkBrf		(ActSeeAllStaCrs+70)
-#define ActRenFolBrf		(ActSeeAllStaCrs+71)
-#define ActRcvFilBrfDZ		(ActSeeAllStaCrs+72)
-#define ActRcvFilBrfCla		(ActSeeAllStaCrs+73)
-#define ActExpBrf		(ActSeeAllStaCrs+74)
-#define ActConBrf		(ActSeeAllStaCrs+75)
-#define ActZIPBrf		(ActSeeAllStaCrs+76)
-#define ActReqDatBrf		(ActSeeAllStaCrs+77)
-#define ActChgDatBrf		(ActSeeAllStaCrs+78)
-#define ActDowBrf		(ActSeeAllStaCrs+79)
+#define ActPrnMyTimTbl		(ActSeeAllStaCrs+60)
+#define ActEdiTut		(ActSeeAllStaCrs+61)
+#define ActChgTut		(ActSeeAllStaCrs+62)
+#define ActReqRemFilBrf		(ActSeeAllStaCrs+63)
+#define ActRemFilBrf		(ActSeeAllStaCrs+64)
+#define ActRemFolBrf		(ActSeeAllStaCrs+65)
+#define ActCopBrf		(ActSeeAllStaCrs+66)
+#define ActPasBrf		(ActSeeAllStaCrs+67)
+#define ActRemTreBrf		(ActSeeAllStaCrs+68)
+#define ActFrmCreBrf		(ActSeeAllStaCrs+69)
+#define ActCreFolBrf		(ActSeeAllStaCrs+70)
+#define ActCreLnkBrf		(ActSeeAllStaCrs+71)
+#define ActRenFolBrf		(ActSeeAllStaCrs+72)
+#define ActRcvFilBrfDZ		(ActSeeAllStaCrs+73)
+#define ActRcvFilBrfCla		(ActSeeAllStaCrs+74)
+#define ActExpBrf		(ActSeeAllStaCrs+75)
+#define ActConBrf		(ActSeeAllStaCrs+76)
+#define ActZIPBrf		(ActSeeAllStaCrs+77)
+#define ActReqDatBrf		(ActSeeAllStaCrs+78)
+#define ActChgDatBrf		(ActSeeAllStaCrs+79)
+#define ActDowBrf		(ActSeeAllStaCrs+80)
 
 /*****************************************************************************/
 /******************************** Public types *******************************/
diff --git a/swad_calendar.c b/swad_calendar.c
index 57546b20..a54a1658 100644
--- a/swad_calendar.c
+++ b/swad_calendar.c
@@ -28,7 +28,11 @@
 #include <string.h>		// For string functions
 
 #include "swad_exam.h"
+#include "swad_calendar.h"
+#include "swad_database.h"
 #include "swad_global.h"
+#include "swad_parameter.h"
+#include "swad_preference.h"
 
 /*****************************************************************************/
 /************** External global variables from others modules ****************/
@@ -40,10 +44,103 @@ extern struct Globals Gbl;
 /**************************** Private constants ******************************/
 /*****************************************************************************/
 
+const bool Cal_DayIsValidAsFirstDayOfWeek[7] =
+  {
+   true,	// 0: monday
+   false,	// 1: tuesday
+   false,	// 2: wednesday
+   false,	// 3: thursday
+   false,	// 4: friday
+   false,	// 5: saturday
+   true,	// 6: sunday
+  };
+
 /*****************************************************************************/
 /***************************** Private prototypes ****************************/
 /*****************************************************************************/
 
+static unsigned Cal_GetParamFirstDayOfWeek (void);
+
+/*****************************************************************************/
+/************** Put icons to select the first day of the week ****************/
+/*****************************************************************************/
+
+void Cal_PutIconsToSelectFirstDayOfWeek (void)
+  {
+   extern const char *Txt_Calendar;
+   extern const char *Txt_First_day_of_the_week;
+   extern const char *Txt_DAYS_SMALL[7];
+   unsigned FirstDayOfWeek;
+
+   Lay_StartRoundFrameTable (NULL,2,Txt_Calendar);
+   fprintf (Gbl.F.Out,"<tr>");
+   for (FirstDayOfWeek = 0;	// Monday
+	FirstDayOfWeek <= 6;	// Sunday
+	FirstDayOfWeek++)
+      if (Cal_DayIsValidAsFirstDayOfWeek[FirstDayOfWeek])
+	{
+	 fprintf (Gbl.F.Out,"<td class=\"%s\">",
+		  FirstDayOfWeek == Gbl.Prefs.FirstDayOfWeek ? "LAYOUT_ON" :
+							       "LAYOUT_OFF");
+	 Act_FormStart (ActChg1stDay);
+	 Par_PutHiddenParamUnsigned ("FirstDayOfWeek",FirstDayOfWeek);
+	 fprintf (Gbl.F.Out,"<input type=\"image\" src=\"%s/first-day-of-week-%u-64x64.png\""
+			    " alt=\"%s\" title=\"%s: %s\" class=\"ICON32x32B\""
+			    " style=\"margin:0 auto;\" />",
+		  Gbl.Prefs.IconsURL,
+		  FirstDayOfWeek,
+		  Txt_DAYS_SMALL[FirstDayOfWeek],
+		  Txt_First_day_of_the_week,Txt_DAYS_SMALL[FirstDayOfWeek]);
+	 Act_FormEnd ();
+	 fprintf (Gbl.F.Out,"</td>");
+        }
+   fprintf (Gbl.F.Out,"</tr>");
+   Lay_EndRoundFrameTable ();
+  }
+
+/*****************************************************************************/
+/************************* Change first day of week **************************/
+/*****************************************************************************/
+
+void Cal_ChangeFirstDayOfWeek (void)
+  {
+   char Query[512];
+
+   /***** Get param with icon set *****/
+   Gbl.Prefs.FirstDayOfWeek = Cal_GetParamFirstDayOfWeek ();
+
+   /***** Store icon set in database *****/
+   if (Gbl.Usrs.Me.Logged)
+     {
+      sprintf (Query,"UPDATE usr_data SET FirstDayOfWeek='%u'"
+	             " WHERE UsrCod='%ld'",
+               Gbl.Prefs.FirstDayOfWeek,
+               Gbl.Usrs.Me.UsrDat.UsrCod);
+      DB_QueryUPDATE (Query,"can not update your preference about first day of week");
+     }
+
+   /***** Set preferences from current IP *****/
+   Pre_SetPrefsFromIP ();
+  }
+
+/*****************************************************************************/
+/*********************** Get parameter with icon set *************************/
+/*****************************************************************************/
+
+static unsigned Cal_GetParamFirstDayOfWeek (void)
+  {
+   char UnsignedStr[10+1];
+   unsigned UnsignedNum;
+   unsigned FirstDayOfWeek = Cal_FIRST_DAY_OF_WEEK_DEFAULT;
+
+   Par_GetParToText ("FirstDayOfWeek",UnsignedStr,10);
+   if (sscanf (UnsignedStr,"%u",&UnsignedNum) == 1)
+      if (Cal_DayIsValidAsFirstDayOfWeek[UnsignedNum])
+	 FirstDayOfWeek = UnsignedNum;
+
+   return FirstDayOfWeek;
+  }
+
 /*****************************************************************************/
 /***************************** Draw current month ****************************/
 /*****************************************************************************/
diff --git a/swad_calendar.h b/swad_calendar.h
index d943d676..6d51f5ba 100644
--- a/swad_calendar.h
+++ b/swad_calendar.h
@@ -31,6 +31,8 @@
 /***************************** Public constants ******************************/
 /*****************************************************************************/
 
+#define Cal_FIRST_DAY_OF_WEEK_DEFAULT	0	// Monday
+
 /*****************************************************************************/
 /******************************* Public types ********************************/
 /*****************************************************************************/
@@ -39,6 +41,9 @@
 /***************************** Public prototypes *****************************/
 /*****************************************************************************/
 
+void Cal_PutIconsToSelectFirstDayOfWeek (void);
+void Cal_ChangeFirstDayOfWeek (void);
+
 void Cal_DrawCurrentMonth (void);
 void Cal_DrawCalendar (void);
 
diff --git a/swad_changelog.h b/swad_changelog.h
index d94f6647..2d590c15 100644
--- a/swad_changelog.h
+++ b/swad_changelog.h
@@ -111,11 +111,17 @@
 /****************************** Public constants *****************************/
 /*****************************************************************************/
 
-#define Log_PLATFORM_VERSION	"SWAD 15.41 (2015/11/21)"
+#define Log_PLATFORM_VERSION	"SWAD 15.42 (2015/11/21)"
 
 // Number of lines (includes comments but not blank lines) has been got with the following command:
 // nl swad*.c swad*.h css/swad*.css py/swad*.py js/swad*.js soap/swad*.h sql/swad*.sql | tail -1
 /*
+        Version 15.42:    Nov 21, 2015	New option in preferences to select first day of the week. (187520 lines)
+					3 changes necessary in database:
+ALTER TABLE IP_prefs ADD COLUMN FirstDayOfWeek TINYINT NOT NULL DEFAULT 0 AFTER LastChange;
+ALTER TABLE usr_data ADD COLUMN FirstDayOfWeek TINYINT NOT NULL DEFAULT 0 AFTER Language,ADD INDEX (FirstDayOfWeek);
+INSERT INTO actions (ActCod,Language,Obsolete,Txt) VALUES ('1484','es','N','Cambiar primer d&iacute;a de semana');
+
         Version 15.41:    Nov 21, 2015	Javascript code to draw a month with sunday as the first day of a week. (187316 lines)
         Version 15.40.8:  Nov 20, 2015	Password is requested only one time when creating a new account. (187309 lines)
         Version 15.40.7:  Nov 20, 2015	New help button to register students in courses without them. (187319 lines)
diff --git a/swad_country.c b/swad_country.c
index ce55bf82..fcb62254 100644
--- a/swad_country.c
+++ b/swad_country.c
@@ -105,7 +105,8 @@ void Cty_SeeCtyWithPendingInss (void)
                         " FROM institutions,countries"
                         " WHERE (institutions.Status & %u)<>0"
                         " AND institutions.CtyCod=countries.CtyCod"
-                        " GROUP BY institutions.CtyCod ORDER BY countries.Name_%s",
+                        " GROUP BY institutions.CtyCod"
+                        " ORDER BY countries.Name_%s",
                   (unsigned) Ins_STATUS_BIT_PENDING,
                   Txt_STR_LANG_ID[Gbl.Prefs.Language]);
          break;
@@ -320,8 +321,10 @@ static void Cty_Configuration (bool PrintView)
 			 "</tr>",
 	       The_ClassForm[Gbl.Prefs.Theme],
 	       Txt_Shortcut,
-	       Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],Gbl.CurrentCty.Cty.CtyCod,
-	       Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],Gbl.CurrentCty.Cty.CtyCod);
+	       Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],
+	       Gbl.CurrentCty.Cty.CtyCod,
+	       Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],
+	       Gbl.CurrentCty.Cty.CtyCod);
 
       if (PrintView)
 	{
diff --git a/swad_course.c b/swad_course.c
index 55436889..3c0f5d92 100644
--- a/swad_course.c
+++ b/swad_course.c
@@ -354,8 +354,10 @@ static void Crs_Configuration (bool PrintView)
                       "</tr>",
             The_ClassForm[Gbl.Prefs.Theme],
             Txt_Shortcut,
-            Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],Gbl.CurrentCrs.Crs.CrsCod,
-            Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],Gbl.CurrentCrs.Crs.CrsCod);
+            Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],
+            Gbl.CurrentCrs.Crs.CrsCod,
+            Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],
+            Gbl.CurrentCrs.Crs.CrsCod);
 
    if (PrintView)
      {
diff --git a/swad_database.c b/swad_database.c
index 639b7e22..607b30ae 100644
--- a/swad_database.c
+++ b/swad_database.c
@@ -88,24 +88,26 @@ void DB_CreateTablesIfNotExist (void)
    /***** Table IP_prefs *****/
 /*
 mysql> DESCRIBE IP_prefs;
-+------------+------------+------+-----+---------+-------+
-| Field      | Type       | Null | Key | Default | Extra |
-+------------+------------+------+-----+---------+-------+
-| IP         | char(15)   | NO   | PRI | NULL    |       |
-| UsrCod     | int(11)    | NO   | MUL | -1      |       |
-| LastChange | datetime   | NO   | MUL | NULL    |       |
-| Layout     | tinyint(4) | NO   |     | 0       |       |
-| Theme      | char(16)   | NO   |     | NULL    |       |
-| IconSet    | char(16)   | NO   |     | NULL    |       |
-| Menu       | tinyint(4) | NO   |     | 0       |       |
-| SideCols   | tinyint(4) | NO   |     | NULL    |       |
-+------------+------------+------+-----+---------+-------+
-8 rows in set (0.00 sec)
++----------------+------------+------+-----+---------+-------+
+| Field          | Type       | Null | Key | Default | Extra |
++----------------+------------+------+-----+---------+-------+
+| IP             | char(15)   | NO   | PRI | NULL    |       |
+| UsrCod         | int(11)    | NO   | MUL | -1      |       |
+| LastChange     | datetime   | NO   | MUL | NULL    |       |
+| FirstDayOfWeek | tinyint(4) | NO   |     | 0       |       |
+| Layout         | tinyint(4) | NO   |     | 0       |       |
+| Theme          | char(16)   | NO   |     | NULL    |       |
+| IconSet        | char(16)   | NO   |     | NULL    |       |
+| Menu           | tinyint(4) | NO   |     | 0       |       |
+| SideCols       | tinyint(4) | NO   |     | NULL    |       |
++----------------+------------+------+-----+---------+-------+
+9 rows in set (0.01 sec)
 */
    DB_CreateTable ("CREATE TABLE IF NOT EXISTS IP_prefs ("
                    "IP CHAR(15) NOT NULL,"
                    "UsrCod INT NOT NULL DEFAULT -1,"
                    "LastChange DATETIME NOT NULL,"
+		   "FirstDayOfWeek TINYINT NOT NULL DEFAULT 0,"
                    "Layout TINYINT NOT NULL DEFAULT 0,"
                    "Theme CHAR(16) NOT NULL,"
                    "IconSet CHAR(16) NOT NULL,"
@@ -2277,6 +2279,7 @@ mysql> DESCRIBE usr_data;
 | Theme             | char(16)                               | NO   | MUL | NULL    |                |
 | IconSet           | char(16)                               | NO   | MUL | NULL    |                |
 | Language          | char(2)                                | NO   | MUL | NULL    |                |
+| FirstDayOfWeek    | tinyint(4)                             | NO   | MUL | 0       |                |
 | Photo             | char(43)                               | NO   |     | NULL    |                |
 | PhotoVisibility   | enum('user','course','system','world') | NO   |     | user    |                |
 | ProfileVisibility | enum('user','course','system','world') | NO   |     | user    |                |
@@ -2299,7 +2302,7 @@ mysql> DESCRIBE usr_data;
 | NotifNtfEvents    | int(11)                                | NO   |     | 0       |                |
 | EmailNtfEvents    | int(11)                                | NO   |     | 0       |                |
 +-------------------+----------------------------------------+------+-----+---------+----------------+
-32 rows in set (0.00 sec)
+33 rows in set (0.00 sec)
 */
    DB_CreateTable ("CREATE TABLE IF NOT EXISTS usr_data ("
                    "UsrCod INT NOT NULL AUTO_INCREMENT,"
@@ -2313,6 +2316,7 @@ mysql> DESCRIBE usr_data;
                    "Theme CHAR(16) NOT NULL,"
                    "IconSet CHAR(16) NOT NULL,"
                    "Language CHAR(2) NOT NULL,"
+		   "FirstDayOfWeek TINYINT NOT NULL DEFAULT 0,"
                    "Photo CHAR(43) NOT NULL,"
 		   "PhotoVisibility ENUM('user','course','system','world') NOT NULL DEFAULT 'user',"
 		   "ProfileVisibility ENUM('user','course','system','world') NOT NULL DEFAULT 'user',"
@@ -2334,7 +2338,7 @@ mysql> DESCRIBE usr_data;
                    "SideCols TINYINT NOT NULL DEFAULT 3,"
                    "NotifNtfEvents INT NOT NULL DEFAULT 0,"
                    "EmailNtfEvents INT NOT NULL DEFAULT 0,"
-                   "PRIMARY KEY(UsrCod),UNIQUE INDEX(EncryptedUsrCod),INDEX(Layout),INDEX(Theme),INDEX(IconSet),INDEX(Language),INDEX(CtyCod),INDEX(InsCtyCod),INDEX(InsCod),INDEX(DptCod),INDEX(CtrCod),INDEX(Menu),INDEX(SideCols))");
+                   "PRIMARY KEY(UsrCod),UNIQUE INDEX(EncryptedUsrCod),INDEX(Layout),INDEX(Theme),INDEX(IconSet),INDEX(Language),INDEX(FirstDayOfWeek),INDEX(CtyCod),INDEX(InsCtyCod),INDEX(InsCod),INDEX(DptCod),INDEX(CtrCod),INDEX(Menu),INDEX(SideCols))");
 
    /***** Table usr_emails *****/
    /*
diff --git a/swad_degree.c b/swad_degree.c
index 78a256e5..7e653ea3 100644
--- a/swad_degree.c
+++ b/swad_degree.c
@@ -414,8 +414,10 @@ static void Deg_Configuration (bool PrintView)
 			 "</tr>",
 	       The_ClassForm[Gbl.Prefs.Theme],
 	       Txt_Shortcut,
-	       Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],Gbl.CurrentDeg.Deg.DegCod,
-	       Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],Gbl.CurrentDeg.Deg.DegCod);
+	       Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],
+	       Gbl.CurrentDeg.Deg.DegCod,
+	       Cfg_HTTPS_URL_SWAD_CGI,Txt_STR_LANG_ID[Gbl.Prefs.Language],
+	       Gbl.CurrentDeg.Deg.DegCod);
 
       if (PrintView)
 	{
diff --git a/swad_enrollment.c b/swad_enrollment.c
index 95b8640f..c2147bba 100644
--- a/swad_enrollment.c
+++ b/swad_enrollment.c
@@ -447,7 +447,7 @@ void Enr_UpdateUsrData (struct UsrData *UsrDat)
    sprintf (Query,"UPDATE usr_data"
 		  " SET Password='%s',"
 		  "Surname1='%s',Surname2='%s',FirstName='%s',Sex='%s',"
-		  "Layout='%u',Theme='%s',IconSet='%s',Language='%s',PhotoVisibility='%s',ProfileVisibility='%s',"
+		  "Layout='%u',Theme='%s',IconSet='%s',Language='%s',FirstDayOfWeek='%u',PhotoVisibility='%s',ProfileVisibility='%s',"
 		  "CtyCod='%ld',"
 		  "LocalAddress='%s',LocalPhone='%s',FamilyAddress='%s',FamilyPhone='%s',OriginPlace='%s',Birthday='%04u-%02u-%02u',Comments='%s'"
 		  " WHERE UsrCod='%ld'",
@@ -458,6 +458,7 @@ void Enr_UpdateUsrData (struct UsrData *UsrDat)
 	    The_ThemeId[UsrDat->Prefs.Theme],
 	    Ico_IconSetId[UsrDat->Prefs.IconSet],
 	    Txt_STR_LANG_ID[UsrDat->Prefs.Language],
+	    UsrDat->Prefs.FirstDayOfWeek,
             Pri_VisibilityDB[UsrDat->PhotoVisibility],
             Pri_VisibilityDB[UsrDat->ProfileVisibility],
 	    UsrDat->CtyCod,
diff --git a/swad_global.c b/swad_global.c
index 09a2d51c..e0443fd0 100644
--- a/swad_global.c
+++ b/swad_global.c
@@ -35,6 +35,7 @@
 #include <unistd.h>		// For getpid
 
 #include "swad_action.h"
+#include "swad_calendar.h"
 #include "swad_config.h"
 #include "swad_constant.h"
 #include "swad_exam.h"
@@ -125,14 +126,15 @@ void Gbl_InitializeGlobals (void)
 
    Gbl.HiddenParamsInsertedIntoDB = false;
 
+   Gbl.Prefs.Language = Txt_Current_CGI_SWAD_Language;
+   Gbl.Prefs.FirstDayOfWeek = Cal_FIRST_DAY_OF_WEEK_DEFAULT;	// Default first day of week
    Gbl.Prefs.Layout = Lay_LAYOUT_DEFAULT;	// Default layout
+   Gbl.Prefs.Menu = Mnu_MENU_DEFAULT;		// Default menu
+   Gbl.Prefs.SideCols = Cfg_DEFAULT_COLUMNS;	// Show both side columns, left and right
    Gbl.Prefs.Theme = The_THEME_DEFAULT;		// Default theme
    Gbl.Prefs.IconSet = Ico_ICON_SET_DEFAULT;	// Default icon set
    sprintf (Gbl.Prefs.IconsURL,"%s/%s",
             Cfg_HTTPS_URL_SWAD_PUBLIC,Cfg_FOLDER_PUBLIC_ICON);
-   Gbl.Prefs.Language = Txt_Current_CGI_SWAD_Language;
-   Gbl.Prefs.Menu = Mnu_MENU_DEFAULT;		// Default menu
-   Gbl.Prefs.SideCols = Cfg_DEFAULT_COLUMNS;	// Show both side columns, left and right
    sprintf (Gbl.Prefs.PathTheme,"%s/%s/%s",
 	    Gbl.Prefs.IconsURL,
 	    Cfg_ICON_FOLDER_THEMES,
diff --git a/swad_global.h b/swad_global.h
index 5fdb197d..1a16021b 100644
--- a/swad_global.h
+++ b/swad_global.h
@@ -130,15 +130,16 @@ struct Globals
      } Imported;
    struct
      {
+      Txt_Language_t Language;
+      unsigned FirstDayOfWeek;
       Lay_Layout_t Layout;
+      Mnu_Menu_t Menu;
+      unsigned SideCols;
       The_Theme_t Theme;
       char PathTheme[PATH_MAX+1];
-      Txt_Language_t Language;
-      unsigned SideCols;
       Ico_IconSet_t IconSet;
       char PathIconSet[PATH_MAX+1];
       char IconsURL[PATH_MAX+1];
-      Mnu_Menu_t Menu;
      } Prefs;
 
    struct
diff --git a/swad_icon.c b/swad_icon.c
index 2b4dc76c..90c89e51 100644
--- a/swad_icon.c
+++ b/swad_icon.c
@@ -46,7 +46,7 @@ extern struct Globals Gbl;
 /******************************** Private constants **************************/
 /*****************************************************************************/
 
-#define MAX_ICON_SET_ID 16
+#define Ico_MAX_BYTES_ICON_SET_ID 16
 
 const char *Ico_IconSetId[Ico_NUM_ICON_SETS] =
   {
@@ -129,17 +129,17 @@ void Ico_ChangeIconSet (void)
 
 Ico_IconSet_t Ico_GetParamIconSet (void)
   {
-   char IconSetId[MAX_ICON_SET_ID+1];
+   char IconSetId[Ico_MAX_BYTES_ICON_SET_ID+1];
    Ico_IconSet_t IconSet;
 
-   Par_GetParToText ("IconSet",IconSetId,MAX_ICON_SET_ID);
+   Par_GetParToText ("IconSet",IconSetId,Ico_MAX_BYTES_ICON_SET_ID);
    for (IconSet = (Ico_IconSet_t) 0;
 	IconSet < Ico_NUM_ICON_SETS;
 	IconSet++)
       if (!strcmp (IconSetId,Ico_IconSetId[IconSet]))
          return IconSet;
 
-   return Ico_ICON_SET_UNKNOWN;
+   return Ico_ICON_SET_DEFAULT;
   }
 
 /*****************************************************************************/
@@ -156,5 +156,5 @@ Ico_IconSet_t Ico_GetIconSetFromStr (const char *Str)
       if (!strcasecmp (Str,Ico_IconSetId[IconSet]))
 	 return IconSet;
 
-   return Ico_ICON_SET_UNKNOWN;
+   return Ico_ICON_SET_DEFAULT;
   }
diff --git a/swad_icon.h b/swad_icon.h
index c28e6688..2a320ebd 100644
--- a/swad_icon.h
+++ b/swad_icon.h
@@ -41,7 +41,6 @@ typedef enum
   {
    Ico_ICON_SET_AWESOME = 0,
    Ico_ICON_SET_NUVOLA  = 1,
-   Ico_ICON_SET_UNKNOWN = 2,
    } Ico_IconSet_t;
 #define Ico_ICON_SET_DEFAULT Ico_ICON_SET_AWESOME
 
diff --git a/swad_message.c b/swad_message.c
index 825f336b..05a9081a 100644
--- a/swad_message.c
+++ b/swad_message.c
@@ -1721,31 +1721,39 @@ static void Msg_ConstructQueryToSelectSentOrReceivedMsgs (char *Query,Msg_TypeOf
             StrUnreadMsg = (Gbl.Msg.ShowOnlyUnreadMsgs ? " AND msg_rcv.Open='N'" :
         	                                         "");
             if (FilterFromToSubquery[0])
-               sprintf (PtrQuery,"SELECT msg_rcv.MsgCod FROM msg_rcv,msg_snt,usr_data"
+               sprintf (PtrQuery,"SELECT msg_rcv.MsgCod"
+        	                 " FROM msg_rcv,msg_snt,usr_data"
                                  " WHERE msg_rcv.UsrCod='%ld'%s"
-                                 " AND msg_rcv.MsgCod=msg_snt.MsgCod AND msg_snt.CrsCod='%ld'"
+                                 " AND msg_rcv.MsgCod=msg_snt.MsgCod"
+                                 " AND msg_snt.CrsCod='%ld'"
                                  " AND msg_snt.UsrCod=usr_data.UsrCod%s"
                                  " ORDER BY msg_rcv.MsgCod DESC",
                         UsrCod,StrUnreadMsg,FilterCrsCod,
                         FilterFromToSubquery);
             else
-               sprintf (PtrQuery,"SELECT msg_rcv.MsgCod FROM msg_rcv,msg_snt"
+               sprintf (PtrQuery,"SELECT msg_rcv.MsgCod"
+        	                 " FROM msg_rcv,msg_snt"
                                  " WHERE msg_rcv.UsrCod='%ld'%s"
-                                 " AND msg_rcv.MsgCod=msg_snt.MsgCod AND msg_snt.CrsCod='%ld'"
+                                 " AND msg_rcv.MsgCod=msg_snt.MsgCod"
+                                 " AND msg_snt.CrsCod='%ld'"
                                  " ORDER BY msg_rcv.MsgCod DESC",
                         UsrCod,StrUnreadMsg,
                         FilterCrsCod);
             break;
          case Msg_MESSAGES_SENT:
             if (FilterFromToSubquery[0])
-               sprintf (PtrQuery,"SELECT DISTINCT msg_snt.MsgCod FROM msg_snt,msg_rcv,usr_data"
-                                 " WHERE msg_snt.UsrCod='%ld' AND msg_snt.CrsCod='%ld'"
-                                 " AND msg_snt.MsgCod=msg_rcv.MsgCod AND msg_rcv.UsrCod=usr_data.UsrCod%s"
+               sprintf (PtrQuery,"SELECT DISTINCT msg_snt.MsgCod"
+        	                 " FROM msg_snt,msg_rcv,usr_data"
+                                 " WHERE msg_snt.UsrCod='%ld'"
+                                 " AND msg_snt.CrsCod='%ld'"
+                                 " AND msg_snt.MsgCod=msg_rcv.MsgCod"
+                                 " AND msg_rcv.UsrCod=usr_data.UsrCod%s"
                                  " ORDER BY msg_snt.MsgCod DESC",
                         UsrCod,FilterCrsCod,
                         FilterFromToSubquery);
             else
-               sprintf (PtrQuery,"SELECT MsgCod FROM msg_snt"
+               sprintf (PtrQuery,"SELECT MsgCod"
+        	                 " FROM msg_snt"
                                  " WHERE UsrCod='%ld' AND CrsCod='%ld'"
                                  " ORDER BY MsgCod DESC",
                         UsrCod,FilterCrsCod);
@@ -1761,9 +1769,11 @@ static void Msg_ConstructQueryToSelectSentOrReceivedMsgs (char *Query,Msg_TypeOf
               {
                StrUnreadMsg = (Gbl.Msg.ShowOnlyUnreadMsgs ? " AND msg_rcv.Open='N'" :
         	                                            "");
-               sprintf (PtrQuery,"SELECT msg_rcv.MsgCod FROM msg_rcv,msg_snt,usr_data"
+               sprintf (PtrQuery,"SELECT msg_rcv.MsgCod"
+        	                 " FROM msg_rcv,msg_snt,usr_data"
                                  " WHERE msg_rcv.UsrCod='%ld'%s"
-                                 " AND msg_rcv.MsgCod=msg_snt.MsgCod AND msg_snt.UsrCod=usr_data.UsrCod%s"
+                                 " AND msg_rcv.MsgCod=msg_snt.MsgCod"
+                                 " AND msg_snt.UsrCod=usr_data.UsrCod%s"
                                  " ORDER BY msg_rcv.MsgCod DESC",
                         UsrCod,StrUnreadMsg,
                         FilterFromToSubquery);
@@ -1772,7 +1782,8 @@ static void Msg_ConstructQueryToSelectSentOrReceivedMsgs (char *Query,Msg_TypeOf
               {
                StrUnreadMsg = (Gbl.Msg.ShowOnlyUnreadMsgs ? " AND Open='N'" :
         	                                            "");
-               sprintf (PtrQuery,"SELECT MsgCod FROM msg_rcv"
+               sprintf (PtrQuery,"SELECT MsgCod"
+        	                 " FROM msg_rcv"
                                  " WHERE UsrCod='%ld'%s"
                                  " ORDER BY MsgCod DESC",
                         UsrCod,StrUnreadMsg);
@@ -1780,14 +1791,17 @@ static void Msg_ConstructQueryToSelectSentOrReceivedMsgs (char *Query,Msg_TypeOf
             break;
          case Msg_MESSAGES_SENT:
             if (FilterFromToSubquery[0])
-               sprintf (PtrQuery,"SELECT DISTINCT msg_snt.MsgCod FROM msg_snt,msg_rcv,usr_data"
+               sprintf (PtrQuery,"SELECT DISTINCT msg_snt.MsgCod"
+        	                 " FROM msg_snt,msg_rcv,usr_data"
                                  " WHERE msg_snt.UsrCod='%ld'"
-                                 " AND msg_snt.MsgCod=msg_rcv.MsgCod AND msg_rcv.UsrCod=usr_data.UsrCod%s"
+                                 " AND msg_snt.MsgCod=msg_rcv.MsgCod"
+                                 " AND msg_rcv.UsrCod=usr_data.UsrCod%s"
                                  " ORDER BY msg_snt.MsgCod DESC",
                         UsrCod,
                         FilterFromToSubquery);
             else
-               sprintf (PtrQuery,"SELECT MsgCod FROM msg_snt"
+               sprintf (PtrQuery,"SELECT MsgCod"
+        	                 " FROM msg_snt"
                                  " WHERE UsrCod='%ld'"
                                  " ORDER BY MsgCod DESC",
                         UsrCod);
@@ -1797,7 +1811,8 @@ static void Msg_ConstructQueryToSelectSentOrReceivedMsgs (char *Query,Msg_TypeOf
         }
 
    if (Gbl.Msg.FilterContent[0])
-      sprintf (Query,"SELECT MsgCod FROM msg_content"
+      sprintf (Query,"SELECT MsgCod"
+	             " FROM msg_content"
                      " WHERE MsgCod IN (%s)"
                      " AND MATCH (Subject,Content) AGAINST ('%s')",
                SubQuery,
diff --git a/swad_nickname.c b/swad_nickname.c
index d956d2d3..a583cb2f 100644
--- a/swad_nickname.c
+++ b/swad_nickname.c
@@ -156,7 +156,8 @@ long Nck_GetUsrCodFromNickname (const char *Nickname)
 
 	 /***** Get user's code from database *****/
 	 /* Check if user code from table usr_nicknames is also in table usr_data */
-	 sprintf (Query,"SELECT usr_nicknames.UsrCod FROM usr_nicknames,usr_data"
+	 sprintf (Query,"SELECT usr_nicknames.UsrCod"
+	                " FROM usr_nicknames,usr_data"
 			" WHERE usr_nicknames.Nickname='%s'"
 			" AND usr_nicknames.UsrCod=usr_data.UsrCod",
 		  NicknameWithoutArroba);
diff --git a/swad_photo.c b/swad_photo.c
index 2f136e84..af1828d7 100644
--- a/swad_photo.c
+++ b/swad_photo.c
@@ -985,7 +985,9 @@ static void Pho_ClearPhotoName (long UsrCod)
    char Query[128];
 
    /***** Clear photo name in user's data *****/
-   sprintf (Query,"UPDATE usr_data SET Photo='' WHERE UsrCod='%ld'",UsrCod);
+   sprintf (Query,"UPDATE usr_data SET Photo=''"
+	          " WHERE UsrCod='%ld'",
+	    UsrCod);
    DB_QueryUPDATE (Query,"can not clear the name of a user's photo");
   }
 
@@ -999,7 +1001,8 @@ void Pho_UpdatePhotoName (struct UsrData *UsrDat)
    char PathPublPhoto[PATH_MAX+1];
 
    /***** Update photo name in database *****/
-   sprintf (Query,"UPDATE usr_data SET Photo='%s' WHERE UsrCod='%ld'",
+   sprintf (Query,"UPDATE usr_data SET Photo='%s'"
+	          " WHERE UsrCod='%ld'",
             Gbl.UniqueNameEncrypted,UsrDat->UsrCod);
    DB_QueryUPDATE (Query,"can not update the name of a user's photo");
 
diff --git a/swad_preference.c b/swad_preference.c
index 380dd985..9117c744 100644
--- a/swad_preference.c
+++ b/swad_preference.c
@@ -30,6 +30,7 @@
 #include <stdio.h>		// For fprintf, etc.
 #include <string.h>
 
+#include "swad_calendar.h"
 #include "swad_config.h"
 #include "swad_database.h"
 #include "swad_global.h"
@@ -67,35 +68,42 @@ void Pre_EditPrefs (void)
    extern const char *Txt_You_can_only_receive_email_notifications_if_;
    char MailDomain[Usr_MAX_BYTES_USR_EMAIL+1];
 
-   /***** Language *****/
+   /***** Language and first day of week *****/
+   fprintf (Gbl.F.Out,"<table style=\"margin:0 auto; border-spacing:16px 0;\">"
+                      "<tr>"
+                      "<td>");
    Lay_StartRoundFrame (NULL,Txt_Language);
-   Pre_PutSelectorToSelectLanguage ();
+   fprintf (Gbl.F.Out,"<div style=\"height:46px;\">");
+   Pre_PutSelectorToSelectLanguage ();		// 1. Language
+   fprintf (Gbl.F.Out,"</div>");
    Lay_EndRoundFrame ();
+   fprintf (Gbl.F.Out,"</td>"
+                      "<td>");
+   Cal_PutIconsToSelectFirstDayOfWeek ();	// 2. First day of week
+   fprintf (Gbl.F.Out,"</td>"
+                      "</tr>"
+	              "</table>");
 
    /***** Layout, side columns, theme, icon set & menu *****/
    fprintf (Gbl.F.Out,"<table style=\"margin:0 auto; border-spacing:16px 0;\">"
                       "<tr>"
                       "<td>");
-   Lay_PutIconsToSelectLayout ();	// 1. Layout
+   Lay_PutIconsToSelectLayout ();		// 3. Layout
    fprintf (Gbl.F.Out,"</td>");
    if (Gbl.Prefs.Layout == Lay_LAYOUT_DESKTOP)
      {
       fprintf (Gbl.F.Out,"<td>");
-      Mnu_PutIconsToSelectMenu ();	// 2. Menu
+      Mnu_PutIconsToSelectMenu ();		// 4. Menu
       fprintf (Gbl.F.Out,"</td>"
                          "<td>");
-      Pre_PutIconsToSelectSideCols ();	// 3. Side columns
+      Pre_PutIconsToSelectSideCols ();		// 5. Side columns
       fprintf (Gbl.F.Out,"</td>");
      }
-   fprintf (Gbl.F.Out,"</tr>"
-	              "</table>"
-                      "<table style=\"margin:0 auto; border-spacing:16px 0;\">"
-                      "<tr>"
-	              "<td>");
-   The_PutIconsToSelectTheme ();	// 4. Theme
+   fprintf (Gbl.F.Out,"<td>");
+   The_PutIconsToSelectTheme ();		// 6. Theme
    fprintf (Gbl.F.Out,"</td>"
                       "<td>");
-   Ico_PutIconsToSelectIconSet ();	// 5. Icon set
+   Ico_PutIconsToSelectIconSet ();		// 7. Icon set
    fprintf (Gbl.F.Out,"</td>"
                       "</tr>"
 	              "</table>");
@@ -178,9 +186,10 @@ void Pre_SetPrefsFromIP (void)
    char Query[512];
 
    /***** Update preferences from current IP in database *****/
-   sprintf (Query,"REPLACE INTO IP_prefs (IP,UsrCod,LastChange,Layout,Theme,IconSet,Menu,SideCols)"
-                  " VALUES ('%s','%ld',NOW(),'%u','%s','%s','%u','%u')",
+   sprintf (Query,"REPLACE INTO IP_prefs (IP,UsrCod,LastChange,FirstDayOfWeek,Layout,Theme,IconSet,Menu,SideCols)"
+                  " VALUES ('%s','%ld',NOW(),'%u','%u','%s','%s','%u','%u')",
             Gbl.IP,Gbl.Usrs.Me.UsrDat.UsrCod,
+            Gbl.Prefs.FirstDayOfWeek,
             (unsigned) Gbl.Prefs.Layout,
             The_ThemeId[Gbl.Prefs.Theme],
             Ico_IconSetId[Gbl.Prefs.IconSet],
@@ -191,8 +200,9 @@ void Pre_SetPrefsFromIP (void)
    /***** If a user is logged, update its preferences in database for all its IP's *****/
    if (Gbl.Usrs.Me.Logged)
      {
-      sprintf (Query,"UPDATE IP_prefs SET Layout='%u',Theme='%s',IconSet='%s',Menu='%u',SideCols='%u'"
+      sprintf (Query,"UPDATE IP_prefs SET FirstDayOfWeek='%u',Layout='%u',Theme='%s',IconSet='%s',Menu='%u',SideCols='%u'"
                      " WHERE UsrCod='%ld'",
+               Gbl.Prefs.FirstDayOfWeek,
                (unsigned) Gbl.Prefs.Layout,
                The_ThemeId[Gbl.Prefs.Theme],
                Ico_IconSetId[Gbl.Prefs.IconSet],
@@ -234,7 +244,8 @@ void Pre_PutSelectorToSelectLanguage (void)
      };
 
    Act_FormStart (ActReqChgLan);
-   fprintf (Gbl.F.Out,"<select name=\"Lan\" style=\"width:%upx; margin:0;\""
+   fprintf (Gbl.F.Out,"<select name=\"Lan\""
+	              " style=\"width:%upx; margin:0;\""
 	              " onchange=\"document.getElementById('%s').submit();\">",
             SelectorWidth[Gbl.Prefs.Layout],Gbl.FormId);
    for (Lan = (Txt_Language_t) 0;
@@ -286,11 +297,8 @@ void Pre_AskChangeLanguage (void)
 void Pre_ChangeLanguage (void)
   {
    extern const char *Txt_STR_LANG_ID[Txt_NUM_LANGUAGES];
-   extern const char *Txt_Your_language_has_changed_to_LANGUAGE;
-   extern const char *Txt_The_language_has_changed_to_LANGUAGE;
    extern const char *Txt_STR_LANG_NAME[Txt_NUM_LANGUAGES];
    char Query[512];
-   bool MyLanguageHasChanged = false;
 
    /***** Get param language *****/
    Gbl.Prefs.Language = Pre_GetParamLanguage ();
@@ -298,20 +306,14 @@ void Pre_ChangeLanguage (void)
    /***** Store language in database *****/
    if (Gbl.Usrs.Me.Logged && Gbl.Prefs.Language != Gbl.Usrs.Me.UsrDat.Prefs.Language)
      {
-      sprintf (Query,"UPDATE usr_data SET Language='%s' WHERE UsrCod='%ld'",
+      sprintf (Query,"UPDATE usr_data SET Language='%s'"
+	             " WHERE UsrCod='%ld'",
                Txt_STR_LANG_ID[Gbl.Prefs.Language],Gbl.Usrs.Me.UsrDat.UsrCod);
       DB_QueryUPDATE (Query,"can not update your language");
-      MyLanguageHasChanged = true;
      }
 
    /***** Set preferences from current IP *****/
    Pre_SetPrefsFromIP ();
-
-   /***** Confirmation *****/
-   if (MyLanguageHasChanged)
-   Lay_ShowAlert (Lay_SUCCESS,
-                  MyLanguageHasChanged ? Txt_Your_language_has_changed_to_LANGUAGE :
-                                         Txt_The_language_has_changed_to_LANGUAGE);
   }
 
 /*****************************************************************************/
@@ -513,7 +515,8 @@ static void Pre_UpdateSideColsOnUsrDataTable (void)
   {
    char Query[512];
 
-   sprintf (Query,"UPDATE usr_data SET SideCols='%u' WHERE UsrCod='%ld'",
+   sprintf (Query,"UPDATE usr_data SET SideCols='%u'"
+	          " WHERE UsrCod='%ld'",
             Gbl.Prefs.SideCols,Gbl.Usrs.Me.UsrDat.UsrCod);
    DB_QueryUPDATE (Query,"can not update your preference about side columns");
   }
diff --git a/swad_record.c b/swad_record.c
index 84f9bea8..b7a2c434 100644
--- a/swad_record.c
+++ b/swad_record.c
@@ -3734,8 +3734,7 @@ void Rec_UpdateMyOffice (void)
    Par_GetParToText ("Office",Gbl.Usrs.Me.UsrDat.Tch.Office,Cns_MAX_BYTES_STRING);
 
    /***** Update office *****/
-   sprintf (Query,"UPDATE usr_data"
-	          " SET Office='%s'"
+   sprintf (Query,"UPDATE usr_data SET Office='%s'"
 	          " WHERE UsrCod='%ld'",
 	    Gbl.Usrs.Me.UsrDat.Tch.Office,
 	    Gbl.Usrs.Me.UsrDat.UsrCod);
@@ -3757,8 +3756,7 @@ void Rec_UpdateMyOfficePhone (void)
    Par_GetParToText ("OfficePhone",Gbl.Usrs.Me.UsrDat.Tch.OfficePhone,Usr_MAX_BYTES_PHONE);
 
    /***** Update office phone *****/
-   sprintf (Query,"UPDATE usr_data"
-	          " SET OfficePhone='%s'"
+   sprintf (Query,"UPDATE usr_data SET OfficePhone='%s'"
 	          " WHERE UsrCod='%ld'",
 	    Gbl.Usrs.Me.UsrDat.Tch.OfficePhone,
 	    Gbl.Usrs.Me.UsrDat.UsrCod);
diff --git a/swad_text.c b/swad_text.c
index b0b6b70e..e2b56720 100644
--- a/swad_text.c
+++ b/swad_text.c
@@ -3578,6 +3578,27 @@ const char *Txt_Calculate_average_photo_of_THE_DEGREE_X =
 	"Calculate average photo of";			// Necessita de tradução
 #endif
 
+const char *Txt_Calendar =
+#if   L==0
+	"Calendari";
+#elif L==1
+	"Kalender";
+#elif L==2
+	"Calendar";
+#elif L==3
+	"Calendario";
+#elif L==4
+	"Calendrier";
+#elif L==5
+	"Arapapaha";
+#elif L==6
+	"Calendario";
+#elif L==7
+	"Kalendarz";
+#elif L==8
+	"Calend&aacute;rio";
+#endif
+
 const char *Txt_Call_the_roll =
 #if   L==0
 	"Passar llista";
@@ -11627,6 +11648,27 @@ const char *Txt_Files_works =
 	"Arquivos trabalhos";
 #endif
 
+const char *Txt_First_day_of_the_week =
+#if   L==0
+	"Primer dia de la setmana";
+#elif L==1
+	"Erster Tag der Woche";
+#elif L==2
+	"First day of the week";
+#elif L==3
+	"Primer d&iacute;a de la semana";
+#elif L==4
+	"Premier jour de la semaine";
+#elif L==5
+	"Primer d&iacute;a de la semana";	// Okoteve traducción
+#elif L==6
+	"Primo giorno della settimana";
+#elif L==7
+	"Pierwszy dzie&nacute; tygodnia";
+#elif L==8
+	"Primeiro dia da semana";
+#endif
+
 const char *Txt_first_message_not_allowed =
 #if   L==0
 	"primer mensaje no permitido";	// Necessita traduccio
@@ -15133,23 +15175,23 @@ const char *Txt_It_is_optional_to_choose_a_group =
 
 const char *Txt_Language =
 #if   L==0
-	"Idioma";
+	"Idioma (language)";
 #elif L==1
-	"Sprache";
+	"Sprache (language)";
 #elif L==2
 	"Language";
 #elif L==3
-	"Idioma";
+	"Idioma (language)";
 #elif L==4
-	"Langue";
+	"Langue (language)";
 #elif L==5
-	"&Ntilde;e'&#7869;";
+	"&Ntilde;e'&#7869; (language)";
 #elif L==6
-	"Lingua";
+	"Lingua (language)";
 #elif L==7
-	"J&eogon;zyk";
+	"J&eogon;zyk (language)";
 #elif L==8
-	"Lingua";
+	"Lingua (language)";
 #endif
 
 const char *Txt_Last_clicks =
@@ -40467,27 +40509,6 @@ const char *Txt_The_integrated_editor_is_not_yet_available =
 	"The integrated editor is not yet available.";			// Necessita de tradução
 #endif
 
-const char *Txt_The_language_has_changed_to_LANGUAGE =
-#if   L==0
-	"S'ha canviat l'idioma a catal&agrave;.";
-#elif L==1
-	"Die Sprache ist nun Deutsch.";
-#elif L==2
-	"The language has changed to English.";
-#elif L==3
-	"Se ha cambiado el idioma a espa&ntilde;ol.";
-#elif L==4
-	"La langue a chang&eacute; au fran&ccedil;ais.";
-#elif L==5
-	"Pe &ntilde;e'&#7869; ha moambuepapyre pe ava&ntilde;e'&#7869;.";
-#elif L==6
-	"La lingua &egrave; cambiata a italiano.";
-#elif L==7
-	"J&eogon;zyk zosta&lstrok; zmieniony na polski.";
-#elif L==8
-	"O idioma mudou para o portugu&ecirc;s.";
-#endif
-
 const char *Txt_The_link_X_already_exists =	// Warning: it is very important to include %s in the following sentences
 #if   L==0
 	"El enlace <strong>%s</strong> ya existe.";	// Necessita traduccio
@@ -51949,27 +51970,6 @@ const char *Txt_Your_comment_has_been_updated =
 	"O seu coment&aacute;rio foi atualizado.";
 #endif
 
-const char *Txt_Your_language_has_changed_to_LANGUAGE =
-#if   L==0
-	"El seu idioma ha canviat a catal&agrave;.";
-#elif L==1
-	"Ihre Sprache ist nun Deutsch.";
-#elif L==2
-	"Your language has changed to English.";
-#elif L==3
-	"Su idioma ha cambiado a espa&ntilde;ol.";
-#elif L==4
-	"Votre langue a chang&eacute; au fran&ccedil;ais.";
-#elif L==5
-	"Pe &ntilde;e'&#7869; ha moambuepapyre pe ava&ntilde;e'&#7869;.";
-#elif L==6
-	"La tua lingua &egrave; cambiata a italiano.";
-#elif L==7
-	"J&eogon;zyk zosta&lstrok; zmieniony na polski.";
-#elif L==8
-	"Suo idioma mudou para o portugu&ecirc;s.";
-#endif
-
 const char *Txt_Your_nickname_X_has_been_registered_successfully =	// Warning: it is very important to include %s in the following sentences
 #if   L==0
 	"Su apodo <strong>@%s</strong>"
diff --git a/swad_theme.c b/swad_theme.c
index 5987f8fa..9c1a75d3 100644
--- a/swad_theme.c
+++ b/swad_theme.c
@@ -276,7 +276,8 @@ void The_ChangeTheme (void)
    /***** Store theme in database *****/
    if (Gbl.Usrs.Me.Logged)
      {
-      sprintf (Query,"UPDATE usr_data SET Theme='%s' WHERE UsrCod='%ld'",
+      sprintf (Query,"UPDATE usr_data SET Theme='%s'"
+	             " WHERE UsrCod='%ld'",
                The_ThemeId[Gbl.Prefs.Theme],Gbl.Usrs.Me.UsrDat.UsrCod);
       DB_QueryUPDATE (Query,"can not update your preference about theme");
      }
diff --git a/swad_user.c b/swad_user.c
index bd087aa4..7ed913b8 100644
--- a/swad_user.c
+++ b/swad_user.c
@@ -36,6 +36,7 @@
 
 #include "swad_account.h"
 #include "swad_announcement.h"
+#include "swad_calendar.h"
 #include "swad_config.h"
 #include "swad_connected.h"
 #include "swad_course.h"
@@ -272,6 +273,7 @@ void Usr_ResetUsrDataExceptUsrCodAndIDs (struct UsrData *UsrDat)
    UsrDat->Tch.OfficePhone[0] = '\0';
 
    UsrDat->Prefs.Language = Cfg_DEFAULT_LANGUAGE_FOR_NEW_USERS;
+   UsrDat->Prefs.FirstDayOfWeek = Cal_FIRST_DAY_OF_WEEK_DEFAULT;	// Default first day of week
    UsrDat->Prefs.Layout = Lay_LAYOUT_DEFAULT;
    UsrDat->Prefs.Theme = The_THEME_DEFAULT;
    UsrDat->Prefs.IconSet = Ico_ICON_SET_DEFAULT;
@@ -359,7 +361,8 @@ void Usr_GetUsrCodFromEncryptedUsrCod (struct UsrData *UsrDat)
    if (UsrDat->EncryptedUsrCod[0])
      {
       /***** Get user's code from database *****/
-      sprintf (Query,"SELECT UsrCod FROM usr_data WHERE EncryptedUsrCod='%s'",
+      sprintf (Query,"SELECT UsrCod FROM usr_data"
+	             " WHERE EncryptedUsrCod='%s'",
                UsrDat->EncryptedUsrCod);
       NumRows = DB_QuerySELECT (Query,&mysql_res,"can not get user's code");
 
@@ -384,6 +387,7 @@ void Usr_GetUsrCodFromEncryptedUsrCod (struct UsrData *UsrDat)
 
 void Usr_GetUsrDataFromUsrCod (struct UsrData *UsrDat)
   {
+   extern const bool Cal_DayIsValidAsFirstDayOfWeek[7];
    extern const char *Txt_STR_LANG_ID[Txt_NUM_LANGUAGES];
    extern const char *The_ThemeId[The_NUM_THEMES];
    extern const char *Ico_IconSetId[Ico_NUM_ICON_SETS];
@@ -399,7 +403,7 @@ void Usr_GetUsrDataFromUsrCod (struct UsrData *UsrDat)
 
    /***** Get user's data from database *****/
    sprintf (Query,"SELECT EncryptedUsrCod,Password,Surname1,Surname2,FirstName,Sex,"
-                  "Layout,Theme,IconSet,Language,Photo,PhotoVisibility,ProfileVisibility,"
+                  "Layout,Theme,IconSet,Language,FirstDayOfWeek,Photo,PhotoVisibility,ProfileVisibility,"
                   "CtyCod,InsCtyCod,InsCod,DptCod,CtrCod,Office,OfficePhone,"
                   "LocalAddress,LocalPhone,FamilyAddress,FamilyPhone,OriginPlace,Birthday,Comments,"
                   "Menu,SideCols,NotifNtfEvents,EmailNtfEvents"
@@ -480,47 +484,53 @@ void Usr_GetUsrDataFromUsrCod (struct UsrData *UsrDat)
          break;
         }
 
-   /* Get rest of data */
-   strncpy (UsrDat->Photo,row[10],sizeof (UsrDat->Photo) - 1);
-   UsrDat->Photo[sizeof (UsrDat->Photo) - 1] = '\0';
-   UsrDat->PhotoVisibility   = Pri_GetVisibilityFromStr (row[11]);
-   UsrDat->ProfileVisibility = Pri_GetVisibilityFromStr (row[12]);
-   UsrDat->CtyCod    = Str_ConvertStrCodToLongCod (row[13]);
-   UsrDat->InsCtyCod = Str_ConvertStrCodToLongCod (row[14]);
-   UsrDat->InsCod    = Str_ConvertStrCodToLongCod (row[15]);
+   /* Get first day of week */
+   UsrDat->Prefs.FirstDayOfWeek = Cal_FIRST_DAY_OF_WEEK_DEFAULT;
+   if (sscanf (row[10],"%u",&UnsignedNum) == 1)
+      if (Cal_DayIsValidAsFirstDayOfWeek[UnsignedNum])
+         UsrDat->Prefs.FirstDayOfWeek = UnsignedNum;
 
-   UsrDat->Tch.DptCod = Str_ConvertStrCodToLongCod (row[16]);
-   UsrDat->Tch.CtrCod = Str_ConvertStrCodToLongCod (row[17]);
-   strncpy (UsrDat->Tch.Office     ,row[18],sizeof (UsrDat->Tch.Office     ) - 1);
+   /* Get rest of data */
+   strncpy (UsrDat->Photo,row[11],sizeof (UsrDat->Photo) - 1);
+   UsrDat->Photo[sizeof (UsrDat->Photo) - 1] = '\0';
+   UsrDat->PhotoVisibility   = Pri_GetVisibilityFromStr (row[12]);
+   UsrDat->ProfileVisibility = Pri_GetVisibilityFromStr (row[13]);
+   UsrDat->CtyCod    = Str_ConvertStrCodToLongCod (row[14]);
+   UsrDat->InsCtyCod = Str_ConvertStrCodToLongCod (row[15]);
+   UsrDat->InsCod    = Str_ConvertStrCodToLongCod (row[16]);
+
+   UsrDat->Tch.DptCod = Str_ConvertStrCodToLongCod (row[17]);
+   UsrDat->Tch.CtrCod = Str_ConvertStrCodToLongCod (row[18]);
+   strncpy (UsrDat->Tch.Office     ,row[19],sizeof (UsrDat->Tch.Office     ) - 1);
    UsrDat->Tch.Office     [sizeof (UsrDat->Tch.Office     ) - 1] = '\0';
-   strncpy (UsrDat->Tch.OfficePhone,row[19],sizeof (UsrDat->Tch.OfficePhone) - 1);
+   strncpy (UsrDat->Tch.OfficePhone,row[20],sizeof (UsrDat->Tch.OfficePhone) - 1);
    UsrDat->Tch.OfficePhone[sizeof (UsrDat->Tch.OfficePhone) - 1] = '\0';
 
-   strncpy (UsrDat->LocalAddress ,row[20],sizeof (UsrDat->LocalAddress ) - 1);
+   strncpy (UsrDat->LocalAddress ,row[21],sizeof (UsrDat->LocalAddress ) - 1);
    UsrDat->LocalAddress [sizeof (UsrDat->LocalAddress ) - 1] = '\0';
-   strncpy (UsrDat->LocalPhone   ,row[21],sizeof (UsrDat->LocalPhone   ) - 1);
+   strncpy (UsrDat->LocalPhone   ,row[22],sizeof (UsrDat->LocalPhone   ) - 1);
    UsrDat->LocalPhone   [sizeof (UsrDat->LocalPhone   ) - 1] = '\0';
-   strncpy (UsrDat->FamilyAddress,row[22],sizeof (UsrDat->FamilyAddress) - 1);
+   strncpy (UsrDat->FamilyAddress,row[23],sizeof (UsrDat->FamilyAddress) - 1);
    UsrDat->FamilyAddress[sizeof (UsrDat->FamilyAddress) - 1] = '\0';
-   strncpy (UsrDat->FamilyPhone  ,row[23],sizeof (UsrDat->FamilyPhone  ) - 1);
+   strncpy (UsrDat->FamilyPhone  ,row[24],sizeof (UsrDat->FamilyPhone  ) - 1);
    UsrDat->FamilyPhone  [sizeof (UsrDat->FamilyPhone  ) - 1] = '\0';
-   strncpy (UsrDat->OriginPlace  ,row[24],sizeof (UsrDat->OriginPlace  ) - 1);
+   strncpy (UsrDat->OriginPlace  ,row[25],sizeof (UsrDat->OriginPlace  ) - 1);
    UsrDat->OriginPlace  [sizeof (UsrDat->OriginPlace  ) - 1] = '\0';
    strcpy (StrBirthday,
-           row[25] ? row[25] :
+           row[26] ? row[26] :
 	             "0000-00-00");
-   Usr_GetUsrCommentsFromString (row[26] ? row[26] :
+   Usr_GetUsrCommentsFromString (row[27] ? row[27] :
 	                                   "",
 	                         UsrDat);        // Get the comments comunes a todas the courses
 
    /* Get menu */
    UsrDat->Prefs.Menu = Mnu_MENU_DEFAULT;
-   if (sscanf (row[27],"%u",&UnsignedNum) == 1)
+   if (sscanf (row[28],"%u",&UnsignedNum) == 1)
       if (UnsignedNum < Mnu_NUM_MENUS)
          UsrDat->Prefs.Menu = (Mnu_Menu_t) UnsignedNum;
 
    /* Get if user wants to show side columns */
-   if (sscanf (row[28],"%u",&UsrDat->Prefs.SideCols) == 1)
+   if (sscanf (row[29],"%u",&UsrDat->Prefs.SideCols) == 1)
      {
       if (UsrDat->Prefs.SideCols > Lay_SHOW_BOTH_COLUMNS)
          UsrDat->Prefs.SideCols = Cfg_DEFAULT_COLUMNS;
@@ -529,11 +539,11 @@ void Usr_GetUsrDataFromUsrCod (struct UsrData *UsrDat)
       UsrDat->Prefs.SideCols = Cfg_DEFAULT_COLUMNS;
 
    /* Get on which events I want to be notified inside the platform */
-   if (sscanf (row[29],"%u",&UsrDat->Prefs.NotifNtfEvents) != 1)
+   if (sscanf (row[30],"%u",&UsrDat->Prefs.NotifNtfEvents) != 1)
       UsrDat->Prefs.NotifNtfEvents = (unsigned) -1;	// 0xFF..FF
 
    /* Get on which events I want to be notified by e-mail */
-   if (sscanf (row[30],"%u",&UsrDat->Prefs.EmailNtfEvents) != 1)
+   if (sscanf (row[31],"%u",&UsrDat->Prefs.EmailNtfEvents) != 1)
       UsrDat->Prefs.EmailNtfEvents = 0;
    if (UsrDat->Prefs.EmailNtfEvents >= (1 << Ntf_NUM_NOTIFY_EVENTS))	// Maximum binary value for NotifyEvents is 000...0011...11
       UsrDat->Prefs.EmailNtfEvents = 0;
@@ -3705,7 +3715,11 @@ static void Usr_BuildQueryToGetUsrsLstCrs (Rol_Role_t Role,const char *UsrQuery,
      }
 
    /***** The last part of the query is for ordering the list *****/
-   strcat (Query," ORDER BY usr_data.Surname1,usr_data.Surname2,usr_data.FirstName,usr_data.UsrCod");
+   strcat (Query," ORDER BY "
+	         "usr_data.Surname1,"
+	         "usr_data.Surname2,"
+	         "usr_data.FirstName,"
+	         "usr_data.UsrCod");
   }
 
 /*****************************************************************************/
@@ -3754,7 +3768,11 @@ void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool
 			      " (SELECT UsrCod FROM usr_data WHERE %s))"
 			      ") AS list_usrs,usr_data"
 			      " WHERE list_usrs.UsrCod=usr_data.UsrCod "
-			      " ORDER BY usr_data.Surname1,usr_data.Surname2,usr_data.FirstName,usr_data.UsrCod",
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
 			(unsigned) Role,UsrQuery,
 			(unsigned) Role,UsrQuery,
 			(unsigned) Role,UsrQuery);
@@ -3773,7 +3791,11 @@ void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool
 			      " WHERE Role='%u' AND Accepted='N')"
 			      ") AS list_usrs,usr_data"
 			      " WHERE list_usrs.UsrCod=usr_data.UsrCod "
-			      " ORDER BY usr_data.Surname1,usr_data.Surname2,usr_data.FirstName,usr_data.UsrCod",
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
 			(unsigned) Role,
 			(unsigned) Role,
 			(unsigned) Role);
@@ -3816,7 +3838,11 @@ void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool
 			      " AND crs_usr.Accepted='N')"
 			      ") AS list_usrs,usr_data"
 			      " WHERE list_usrs.UsrCod=usr_data.UsrCod "
-			      " ORDER BY usr_data.Surname1,usr_data.Surname2,usr_data.FirstName,usr_data.UsrCod",
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
 			UsrQuery,Gbl.CurrentCty.Cty.CtyCod,(unsigned) Role,
 			UsrQuery,Gbl.CurrentCty.Cty.CtyCod,(unsigned) Role,
 			UsrQuery,Gbl.CurrentCty.Cty.CtyCod,(unsigned) Role);
@@ -3854,7 +3880,11 @@ void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool
 			      " AND crs_usr.Accepted='N')"
 			      ") AS list_usrs,usr_data"
 			      " WHERE list_usrs.UsrCod=usr_data.UsrCod "
-			      " ORDER BY usr_data.Surname1,usr_data.Surname2,usr_data.FirstName,usr_data.UsrCod",
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
 			Gbl.CurrentCty.Cty.CtyCod,(unsigned) Role,
 			Gbl.CurrentCty.Cty.CtyCod,(unsigned) Role,
 			Gbl.CurrentCty.Cty.CtyCod,(unsigned) Role);
@@ -3894,7 +3924,11 @@ void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool
 			      " AND crs_usr.Accepted='N')"
 			      ") AS list_usrs,usr_data"
 			      " WHERE list_usrs.UsrCod=usr_data.UsrCod "
-			      " ORDER BY usr_data.Surname1,usr_data.Surname2,usr_data.FirstName,usr_data.UsrCod",
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
 			UsrQuery,Gbl.CurrentIns.Ins.InsCod,(unsigned) Role,
 			UsrQuery,Gbl.CurrentIns.Ins.InsCod,(unsigned) Role,
 			UsrQuery,Gbl.CurrentIns.Ins.InsCod,(unsigned) Role);
@@ -3929,7 +3963,11 @@ void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool
 			      " AND crs_usr.Accepted='N')"
 			      ") AS list_usrs,usr_data"
 			      " WHERE list_usrs.UsrCod=usr_data.UsrCod "
-			      " ORDER BY usr_data.Surname1,usr_data.Surname2,usr_data.FirstName,usr_data.UsrCod",
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
 			Gbl.CurrentIns.Ins.InsCod,(unsigned) Role,
 			Gbl.CurrentIns.Ins.InsCod,(unsigned) Role,
 			Gbl.CurrentIns.Ins.InsCod,(unsigned) Role);
@@ -3966,7 +4004,11 @@ void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool
 			      " AND crs_usr.Accepted='N')"
 			      ") AS list_usrs,usr_data"
 			      " WHERE list_usrs.UsrCod=usr_data.UsrCod "
-			      " ORDER BY usr_data.Surname1,usr_data.Surname2,usr_data.FirstName,usr_data.UsrCod",
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
 			UsrQuery,Gbl.CurrentCtr.Ctr.CtrCod,(unsigned) Role,
 			UsrQuery,Gbl.CurrentCtr.Ctr.CtrCod,(unsigned) Role,
 			UsrQuery,Gbl.CurrentCtr.Ctr.CtrCod,(unsigned) Role);
@@ -3998,7 +4040,11 @@ void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool
 			      " AND crs_usr.Accepted='N')"
 			      ") AS list_usrs,usr_data"
 			      " WHERE list_usrs.UsrCod=usr_data.UsrCod "
-			      " ORDER BY usr_data.Surname1,usr_data.Surname2,usr_data.FirstName,usr_data.UsrCod",
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
 			Gbl.CurrentCtr.Ctr.CtrCod,(unsigned) Role,
 			Gbl.CurrentCtr.Ctr.CtrCod,(unsigned) Role,
 			Gbl.CurrentCtr.Ctr.CtrCod,(unsigned) Role);
@@ -4032,7 +4078,11 @@ void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool
 			      " AND crs_usr.Accepted='N')"
 			      ") AS list_usrs,usr_data"
 			      " WHERE list_usrs.UsrCod=usr_data.UsrCod "
-			      " ORDER BY usr_data.Surname1,usr_data.Surname2,usr_data.FirstName,usr_data.UsrCod",
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
 			UsrQuery,Gbl.CurrentDeg.Deg.DegCod,(unsigned) Role,
 			UsrQuery,Gbl.CurrentDeg.Deg.DegCod,(unsigned) Role,
 			UsrQuery,Gbl.CurrentDeg.Deg.DegCod,(unsigned) Role);
@@ -4058,7 +4108,11 @@ void Usr_GetUsrsLst (Rol_Role_t Role,Sco_Scope_t Scope,const char *UsrQuery,bool
 			      " AND crs_usr.Accepted='N')"
 			      ") AS list_usrs,usr_data"
 			      " WHERE list_usrs.UsrCod=usr_data.UsrCod "
-			      " ORDER BY usr_data.Surname1,usr_data.Surname2,usr_data.FirstName,usr_data.UsrCod",
+			      " ORDER BY "
+			      "usr_data.Surname1,"
+			      "usr_data.Surname2,"
+			      "usr_data.FirstName,"
+			      "usr_data.UsrCod",
 			Gbl.CurrentDeg.Deg.DegCod,(unsigned) Role,
 			Gbl.CurrentDeg.Deg.DegCod,(unsigned) Role,
 			Gbl.CurrentDeg.Deg.DegCod,(unsigned) Role);
@@ -4098,8 +4152,11 @@ static void Usr_GetAdmsLst (Sco_Scope_t Scope)
                        " WHERE (admin.Scope='Deg'"
                        " OR admin.Scope='Sys')"
                        " AND admin.UsrCod=usr_data.UsrCod "
-                       " ORDER BY usr_data.Surname1,usr_data.Surname2,"
-                       "usr_data.FirstName,usr_data.UsrCod");
+                       " ORDER BY "
+                       "usr_data.Surname1,"
+                       "usr_data.Surname2,"
+                       "usr_data.FirstName,"
+                       "usr_data.UsrCod");
          break;
       case Sco_SCOPE_INS:
          sprintf (Query,"SELECT DISTINCT admin.UsrCod,'Y',usr_data.Sex"
@@ -4110,8 +4167,11 @@ static void Usr_GetAdmsLst (Sco_Scope_t Scope)
                         " AND admin.Scope='Deg')"
                         " OR admin.Scope='Sys')"
                         " AND admin.UsrCod=usr_data.UsrCod "
-                        " ORDER BY usr_data.Surname1,usr_data.Surname2,"
-                        "usr_data.FirstName,usr_data.UsrCod",
+                        " ORDER BY "
+                        "usr_data.Surname1,"
+                        "usr_data.Surname2,"
+                        "usr_data.FirstName,"
+                        "usr_data.UsrCod",
                   Gbl.CurrentIns.Ins.InsCod);
          break;
       case Sco_SCOPE_CTR:
@@ -4122,8 +4182,11 @@ static void Usr_GetAdmsLst (Sco_Scope_t Scope)
                         " AND admin.Scope='Deg')"
                         " OR admin.Scope='Sys')"
                         " AND admin.UsrCod=usr_data.UsrCod "
-                        " ORDER BY usr_data.Surname1,usr_data.Surname2,"
-                        "usr_data.FirstName,usr_data.UsrCod",
+                        " ORDER BY "
+                        "usr_data.Surname1,"
+                        "usr_data.Surname2,"
+                        "usr_data.FirstName,"
+                        "usr_data.UsrCod",
                   Gbl.CurrentCtr.Ctr.CtrCod);
          break;
       case Sco_SCOPE_DEG:
@@ -4132,8 +4195,11 @@ static void Usr_GetAdmsLst (Sco_Scope_t Scope)
                         " WHERE ((admin.Scope='Deg' AND admin.Cod='%ld')"
                         " OR admin.Scope='Sys')"
                         " AND admin.UsrCod=usr_data.UsrCod "
-                        " ORDER BY usr_data.Surname1,usr_data.Surname2,"
-                        "usr_data.FirstName,usr_data.UsrCod",
+                        " ORDER BY "
+                        "usr_data.Surname1,"
+                        "usr_data.Surname2,"
+                        "usr_data.FirstName,"
+                        "usr_data.UsrCod",
                   Gbl.CurrentDeg.Deg.DegCod);
          break;
       default:        // not aplicable
diff --git a/swad_user.h b/swad_user.h
index ac2724c9..f294b23d 100644
--- a/swad_user.h
+++ b/swad_user.h
@@ -151,6 +151,7 @@ struct UsrData
    struct
      {
       Txt_Language_t Language;
+      unsigned FirstDayOfWeek;
       Lay_Layout_t Layout;
       The_Theme_t Theme;
       Ico_IconSet_t IconSet;
diff --git a/swad_web_service.c b/swad_web_service.c
index fbed2c8f..aab58ab4 100644
--- a/swad_web_service.c
+++ b/swad_web_service.c
@@ -2721,7 +2721,8 @@ static int Svc_GetLanguageFromUsrCod (long UsrCod)
    Txt_Language_t Lan;
 
    /***** Get user's language *****/
-   sprintf (Query,"SELECT Language FROM usr_data WHERE UsrCod='%ld'",
+   sprintf (Query,"SELECT Language FROM usr_data"
+	          " WHERE UsrCod='%ld'",
 	    UsrCod);
    if (DB_QuerySELECT (Query,&mysql_res,"can not get user's language") != 1)
       return soap_receiver_fault (Gbl.soap,
@@ -2906,7 +2907,8 @@ int swad__sendMessage (struct soap *soap,
 
    /***** Build query for recipients from database *****/
    if (ReplyUsrCod > 0)
-      sprintf (Query,"SELECT UsrCod FROM usr_data WHERE UsrCod='%ld'",
+      sprintf (Query,"SELECT UsrCod FROM usr_data"
+	             " WHERE UsrCod='%ld'",
 	       ReplyUsrCod);
    else
       Query[0] = '\0';