diff --git a/C/c_interface.c b/C/c_interface.c
index 9152df9c2..34fd93543 100644
--- a/C/c_interface.c
+++ b/C/c_interface.c
@@ -10,8 +10,11 @@
 * File:		c_interface.c						 *
 * comments:	c_interface primitives definition 			 *
 *									 *
-* Last rev:	$Date: 2008-02-12 17:03:50 $,$Author: vsc $						 *
+* Last rev:	$Date: 2008-03-13 18:41:50 $,$Author: vsc $						 *
 * $Log: not supported by cvs2svn $
+* Revision 1.106  2008/02/12 17:03:50  vsc
+* SWI-portability changes
+*
 * Revision 1.105  2008/01/28 10:42:19  vsc
 * fix BOM trouble
 *
@@ -1681,6 +1684,9 @@ YAP_Init(YAP_init_args *yap_init)
 	      yap_init->DelayedReleaseLoad
 	      );
   Yap_InitExStacks (Trail, Stack);
+  if (yap_init->QuietMode) {
+    yap_flags[QUIET_MODE_FLAG] = TRUE;
+  }
 
 { BACKUP_MACHINE_REGS();
   Yap_InitYaamRegs();
@@ -1773,6 +1779,9 @@ YAP_Init(YAP_init_args *yap_init)
   if (yap_init->YapPrologAddPath) {
     Yap_PutValue(Yap_FullLookupAtom("$extend_file_search_path"), MkAtomTerm(Yap_LookupAtom(yap_init->YapPrologAddPath)));
   }
+  if (yap_init->QuietMode) {
+    yap_flags[QUIET_MODE_FLAG] = TRUE;
+  }
   if (yap_init->SavedState != NULL ||
       yap_init->YapPrologBootFile == NULL) {
     if (restore_result == FAIL_RESTORE) {
@@ -1816,6 +1825,7 @@ YAP_FastInit(char saved_state[])
   init_args.Argv = NULL;
   init_args.ErrorNo = 0;
   init_args.ErrorCause = NULL;
+  init_args.QuietMode = FALSE;
   out = YAP_Init(&init_args);
   if (out == YAP_BOOT_FROM_SAVED_ERROR) {
     Yap_Error(init_args.ErrorNo,TermNil,init_args.ErrorCause);
diff --git a/C/init.c b/C/init.c
index 838bdf3be..58fc565b7 100644
--- a/C/init.c
+++ b/C/init.c
@@ -859,6 +859,7 @@ InitFlags(void)
   /* current default */
   yap_flags[INDEXING_MODE_FLAG] = INDEX_MODE_MULTI;
   yap_flags[TABLING_MODE_FLAG] = 0;
+  yap_flags[QUIET_MODE_FLAG] = FALSE;
 }
 
 static void 
diff --git a/C/save.c b/C/save.c
index 2790f0e89..998c9d1e7 100644
--- a/C/save.c
+++ b/C/save.c
@@ -1398,7 +1398,7 @@ commit_to_saved_state(char *s, CELL *Astate, CELL *ATrail, CELL *AStack, CELL *A
     return(FAIL_RESTORE);
   Yap_PrologMode = BootMode;
   if (Yap_HeapBase) {
-    if (!yap_flags[HALT_AFTER_CONSULT_FLAG]) {
+    if (!yap_flags[HALT_AFTER_CONSULT_FLAG] && !yap_flags[QUIET_MODE_FLAG]) {
       Yap_TrueFileName(s,Yap_FileNameBuf2, YAP_FILENAME_MAX);
       fprintf(stderr, "%% Restoring file %s\n", Yap_FileNameBuf2);
     }
diff --git a/H/Yap.h b/H/Yap.h
index 4ead7b25c..8fb19e8c9 100644
--- a/H/Yap.h
+++ b/H/Yap.h
@@ -10,7 +10,7 @@
 * File:		Yap.h.m4						 *
 * mods:									 *
 * comments:	main header file for YAP				 *
-* version:      $Id: Yap.h,v 1.27 2008-02-12 21:50:58 vsc Exp $	 *
+* version:      $Id: Yap.h,v 1.28 2008-03-13 18:41:50 vsc Exp $	 *
 *************************************************************************/
 
 #include "config.h"
@@ -521,8 +521,9 @@ typedef enum
   INDEXING_MODE_FLAG = 19,
   TABLING_MODE_FLAG = 20,
   VARS_CAN_HAVE_QUOTE_FLAG = 21,
+  QUIET_MODE_FLAG = 22,
   /* let this be the last one */
-  LAST_FLAG = 22
+  LAST_FLAG = 23
 } yap_flags;
 
 #define STRING_AS_CHARS		0
diff --git a/changes-5.1.html b/changes-5.1.html
index e9d159648..4eeab30ee 100644
--- a/changes-5.1.html
+++ b/changes-5.1.html
@@ -17,6 +17,10 @@ xb
 
 <h2>Yap-5.1.3:</h2>
 <ul>
+<li> NEW: upgrade clpqr and chr (SWI compatibility).</li>
+<li> NEW: expects_dialect/1 directive (SWI compatibility).</li>
+<li> NEW: terms:unifiable/3 (SWI compatibility).</li>
+<li> NEW: -q flag  for silent booting (request from Nicos Angelopoulos).</li>
 <li> NEW: verbose prolog_flag fixes silent (obs from Nicos
 Angelopoulos).</li>
 <li> FIXED: true_file_name/3 was totally broken (obs from Nicos Angelopoulos).</li>
diff --git a/console/yap.c b/console/yap.c
index de7319616..7b2c2632f 100644
--- a/console/yap.c
+++ b/console/yap.c
@@ -233,8 +233,10 @@ print_usage(void)
   fprintf(stderr,"\n[ Valid switches for command line arguments: ]\n");
   fprintf(stderr,"  -?   Shows this screen\n");
   fprintf(stderr,"  -b   Boot file \n");
+  fprintf(stderr,"  -f   Do not consult startup prolog files\n");
   fprintf(stderr,"  -g   Run Goal Before Top-Level \n");
   fprintf(stderr,"  -z   Run Goal Before Top-Level \n");
+  fprintf(stderr,"  -q   start with informational messages off\n");
   fprintf(stderr,"  -l   load Prolog file\n");
   fprintf(stderr,"  -L   run Prolog file and exit\n");
   fprintf(stderr,"  -p   extra path for file-search-path\n");
@@ -295,6 +297,9 @@ parse_yap_arguments(int argc, char *argv[], YAP_init_args *iap)
           case '?':
 	    print_usage();
             exit(EXIT_SUCCESS);
+          case 'q':
+	    iap->QuietMode = TRUE;
+	    break;
 	  case 'w':
 	    ssize = &(iap->NumberWorkers);
 	    goto GetSize;
@@ -432,7 +437,8 @@ parse_yap_arguments(int argc, char *argv[], YAP_init_args *iap)
 	    break;
 #endif
 	  case 'L':
-           iap->HaltAfterConsult = TRUE;
+	    iap->QuietMode = TRUE;
+	    iap->HaltAfterConsult = TRUE;
 	  case 'l':
            p++;
 	   if (!*++argv) {
@@ -590,6 +596,7 @@ init_standard_system(int argc, char *argv[], YAP_init_args *iap)
 #endif  
   iap->ErrorNo = 0;
   iap->ErrorCause = NULL;
+  iap->QuietMode = FALSE;
 
   BootMode = parse_yap_arguments(argc,argv,iap);
 
diff --git a/docs/yap.tex b/docs/yap.tex
index 64dc5ec4f..a4bc92cce 100644
--- a/docs/yap.tex
+++ b/docs/yap.tex
@@ -890,6 +890,10 @@ the predicate '$live'/0.
 connect standard streams to host @t{IP_HOST} at port @t{port}
 @item filename
 restore state saved in the given file
+@item -f
+do not consult initial files
+@item -q
+do not print informational messages
 @item --
 separator for arguments to Prolog code. These arguments are visible
 through the unix/1 built-in.
@@ -10509,6 +10513,14 @@ variable in @var{Term1}.
 Succeed if the second argument @var{Var} is a variable and occurs in
 term @var{Term}.
 
+@item unifiable(?@var{Term1}, ?@var{Term2}, -@var{Bindings})
+@findex  unifiable/3
+@syindex unifiable/3
+@cnindex unifiable/3
+
+Succeed if @var{Term1} and @var{Term2} are unifiable with substitution
+@var{Bindings}.
+
 @end table
 
 @node Tries, Cleanup, Terms, Library
diff --git a/include/yap_structs.h b/include/yap_structs.h
index 0dbb17f69..bbdd2761a 100644
--- a/include/yap_structs.h
+++ b/include/yap_structs.h
@@ -114,6 +114,8 @@ typedef struct {
   int Argc;
   /* array of arguments as seen by Prolog */
   char **Argv;
+  /* QuietMode */
+  int QuietMode;
 #ifdef MYDDAS_MYSQL
   /* If any myddas option was given */
   short myddas;
diff --git a/pl/boot.yap b/pl/boot.yap
index 0a70cf50e..f17d98db4 100644
--- a/pl/boot.yap
+++ b/pl/boot.yap
@@ -40,11 +40,20 @@ true :- true.
 	'$change_alias_to_stream'('$loop_stream','$stream'(0)),
         % do catch as early as possible
 	(
-	 '$access_yap_flags'(15, 0), \+ '$uncaught_throw' ->
+	 '$access_yap_flags'(15, 0),
+	 '$access_yap_flags'(22, 0),
+	 \+ '$uncaught_throw'
+	->
 	  '$version'
 	;
 	  true
 	),
+	(
+	 '$access_yap_flags'(22, 0) ->
+	 set_value('$verbose',on)
+	;
+	 set_value('$verbose',off)
+	),
 	(
 	 retractall(user:library_directory(_)),
 	 '$system_library_directories'(D),
diff --git a/pl/directives.yap b/pl/directives.yap
index 7c67a1255..3ace083fb 100644
--- a/pl/directives.yap
+++ b/pl/directives.yap
@@ -320,16 +320,24 @@ yap_flag(tabling_mode,Options) :-
 
 yap_flag(informational_messages,X) :- var(X), !,
 	 get_value('$verbose',X).
-yap_flag(informational_messages,on)  :- !, set_value('$verbose',on).
-yap_flag(informational_messages,off) :- !, set_value('$verbose',off).
+yap_flag(informational_messages,on)  :- !,
+	set_value('$verbose',on),
+	'$set_yap_flags'(22,0).
+yap_flag(informational_messages,off) :- !,
+	set_value('$verbose',off),
+	'$set_yap_flags'(22,1).
 yap_flag(informational_messages,X) :-
 	'$do_error'(domain_error(flag_value,informational_messages+X),yap_flag(informational_messages,X)).
 
 yap_flag(verbose,X) :- var(X), !,
 	 get_value('$verbose',X0),
 	 (X0 == on -> X = normal ; X = silent).
-yap_flag(verbose,normal)  :- !, set_value('$verbose',on).
-yap_flag(verbose,silent) :- !, set_value('$verbose',off).
+yap_flag(verbose,normal)  :- !,
+	set_value('$verbose',on),
+	'$set_yap_flags'(22,0).
+yap_flag(verbose,silent) :- !,
+	set_value('$verbose',off),
+	'$set_yap_flags'(22,1).
 yap_flag(verbose,X) :-
 	'$do_error'(domain_error(flag_value,verbose+X),yap_flag(verbose,X)).