diff --git a/include/isam.cpp b/include/isam.cpp
index 4cf42cb7d..d4bfedd25 100755
--- a/include/isam.cpp
+++ b/include/isam.cpp
@@ -139,7 +139,7 @@ HIDDEN void getisfd(isfdptr & isfd, int logicnum)
   isfd->d = new FileDes ;
   CGetFile(logicnum, isfd->d, _nolock, _nordir);
   const TFixed_string name(isfd->d->SysName);
-  if (name.not_empty() && name[0] ==  '%')
+  if (name.not_empty() && name[0] != '$')
     isfd->ft = _comdir;
   else
     isfd->ft = _nordir;
@@ -1369,36 +1369,39 @@ int TSystemisamfile::build(TRecnotype eox)
   
   d.get(num());
   r.get(num());
+  CHECK(r.len() != 0, "Can't create a file with empty field info");
   
   TFilename f(d.name());
 
   f = f.path(); if (!is_not_slash(f.right(1)[0])) f.rtrim(1);
   if (!fexist(f)) 
     make_dir(f);
-  err=DB_build(d.name(),r.rec());
-  if (err == NOERR) 
-  {
-    isfdptr i;
-    getisfd(i,num()); 
-    i->d->EOX = eox;
-    relisfd(i);
-  }
-  else
-    err = get_error(err);
-  setstatus(err);
-  clearfilehnd();
-  
+  if (r.len() != 0)
+  {  
+    err=DB_build(d.name(),r.rec());
+    if (err == NOERR) 
+    {
+      isfdptr i;
+      getisfd(i,num()); 
+      i->d->EOX = eox;
+      relisfd(i);
+    }
+    else
+      err = get_error(err);
+    setstatus(err);
+    clearfilehnd();
+    
 #ifndef FOXPRO  
-  if (err == NOERR && __autoload)
-  {
-    TFilename lf;
-
-    lf.format("%sstd/lf%04d.txt", __ptprf, num());
-    if (fexist(lf))
-      load(lf, '|', '\0', '\n', TRUE, TRUE);
-  }
+    if (err == NOERR && __autoload)
+    {
+      TFilename lf;
+      
+      lf.format("%sstd/lf%04d.txt", __ptprf, num());
+      if (fexist(lf))
+        load(lf, '|', '\0', '\n', TRUE, TRUE);
+    }
 #endif
-  
+  }
   return err;
 }
 
@@ -1520,7 +1523,8 @@ int TSystemisamfile::update(TTrec& newrec, bool vis)
   
 {        
   CHECKS(filehnd() == NULL, "Can't update open file", (const char*)filename());
-
+  CHECK(newrec.len() != 0, "Can't update to file with empty field info");
+  
   TDir           dir;
 
   dir.get(num(), _unlock, _nordir, _sysdirop);
@@ -1532,110 +1536,113 @@ int TSystemisamfile::update(TTrec& newrec, bool vis)
   TTrec  oldrec;
 
   oldrec.get(num());
-  const long lev = prefix().filelevel();
-  const bool lcf = getlcf(lev);
-  exec_convapp(lev, TRUE);
-
-  if (!lcf && newrec == oldrec)
+  if (newrec.len() != 0)
   {
-    exec_convapp(lev, FALSE);
-    return NOERR;
-  }
-
-  const TRecnotype nitems = dir.eod();
-  const unsigned int lenr = newrec.len();
-
-  if (!toconvert && dir.eox() > 0L)
-  {
-    dir.eod() = 0L; 
-    dir.eox() = 0L;
-  }
-
-  if (toconvert && dir.eox() > 0L)
-  {
-    TRecnotype ni = 0L;     
-    isfdptr i0;  
-    TFilename tmpfname("tmpf");  
+    const long lev = prefix().filelevel();
+    const bool lcf = getlcf(lev);
+    exec_convapp(lev, TRUE);
     
-    open(_excllock);
-    getisfd(i0, num());
-    err=DB_build((const char*) tmpfname, newrec.rec());
-    if (err != NOERR) 
+    if (!lcf && newrec == oldrec)
     {
-      err=get_error(err);
-      return (err);
+      exec_convapp(lev, FALSE);
+      return NOERR;
     }
-    i0->fhnd=DB_open((const char*)tmpfname,0);
-    if (i0->fhnd < 0 ) err=get_error(i0->fhnd);
-    TFilename fname(filename());
-    TString s(80);
-    s.format("Aggiornamento archivio %s", (const char*) fname);
-    TProgind p(nitems ? nitems : 1, s, TRUE, TRUE, 70);
-    int nflds = curr().items();
-    TArray  fld(nflds);
-    TExtrectype nrec(newrec);
-    TRecnotype i = 0;
-
-    for (int j = 0; j < nflds; j++)
-      fld.add(TString(curr().fieldname(j)), j);
-
-    for (first(); good(); next())
+    
+    const TRecnotype nitems = dir.eod();
+    const unsigned int lenr = newrec.len();
+    
+    if (!toconvert && dir.eox() > 0L)
     {
-      if ((i++ % 50) == 0) p.setstatus(i + 1);
-      nrec.zero();
-      ni++;
-      for (j = 0; j < nflds; j++)
-        if (nrec.exist((const TString&) fld[j]))
-          nrec.put((const TString&) fld[j], get((const TString&) fld[j]));
-      if (lcf)
-        makelc((TRectype &)nrec);
-      memcpy(DB_getrecord(i0->fhnd),nrec.string(),DB_reclen(i0->fhnd));  
-      err=DB_add(i0->fhnd);
-      if (err != NOERR) err=get_error(err);
-      setstatus(err);
+      dir.eod() = 0L; 
+      dir.eox() = 0L;
     }
-    err=DB_close(i0->fhnd);      
-    close();
-    if (err!=NOERR) err=get_error(err);
-    relisfd(i0);
-    p.setstatus(nitems);
-    if (err == NOERR)
-    {           
-      long c = DB_getconf();
-      fname.ext("dbf");
-      tmpfname.ext("dbf");
-      fcopy((const char*)tmpfname,(const char*)fname);
-      ::remove((const char*)tmpfname);
-      if (c & 1)                        // FOXPRO format
-        tmpfname.ext("cdx");
-      if (c & 4)                        // DBIV format
-        tmpfname.ext("mdx");
-      if (c & 8 || c & 2)
-      {                   
-        tmpfname.ext("cgp");
-        char in[16];    
-        FILE *fp=fopen((const char *) tmpfname,"r");
-        while (fgets(in,16,fp)!=NULL)
-        {
-          TFilename a(in);          
-          a.rtrim(1); // Cut \n
-          if (c & 8)                    // DBIII format
-            a.ext("ndx");
-          else
-            a.ext("ntx");       // CLIPPER format
-          ::remove((const char *)a);
-        }
-        fclose(fp);
+    
+    if (toconvert && dir.eox() > 0L)
+    {
+      TRecnotype ni = 0L;     
+      isfdptr i0;  
+      TFilename tmpfname("tmpf");  
+      
+      open(_excllock);
+      getisfd(i0, num());
+      err=DB_build((const char*) tmpfname, newrec.rec());
+      if (err != NOERR) 
+      {
+        err=get_error(err);
+        return (err);
+      }
+      i0->fhnd=DB_open((const char*)tmpfname,0);
+      if (i0->fhnd < 0 ) err=get_error(i0->fhnd);
+      TFilename fname(filename());
+      TString s(80);
+      s.format("Aggiornamento archivio %s", (const char*) fname);
+      TProgind p(nitems ? nitems : 1, s, TRUE, TRUE, 70);
+      int nflds = curr().items();
+      TArray  fld(nflds);
+      TExtrectype nrec(newrec);
+      TRecnotype i = 0;
+      
+      for (int j = 0; j < nflds; j++)
+        fld.add(TString(curr().fieldname(j)), j);
+      
+      for (first(); good(); next())
+      {
+        if ((i++ % 50) == 0) p.setstatus(i + 1);
+        nrec.zero();
+        ni++;
+        for (j = 0; j < nflds; j++)
+          if (nrec.exist((const TString&) fld[j]))
+            nrec.put((const TString&) fld[j], get((const TString&) fld[j]));
+        if (lcf)
+          makelc((TRectype &)nrec);
+        memcpy(DB_getrecord(i0->fhnd),nrec.string(),DB_reclen(i0->fhnd));  
+        err=DB_add(i0->fhnd);
+        if (err != NOERR) err=get_error(err);
+        setstatus(err);
+      }
+      err=DB_close(i0->fhnd);      
+      close();
+      if (err!=NOERR) err=get_error(err);
+      relisfd(i0);
+      p.setstatus(nitems);
+      if (err == NOERR)
+      {           
+        long c = DB_getconf();
+        fname.ext("dbf");
+        tmpfname.ext("dbf");
+        fcopy((const char*)tmpfname,(const char*)fname);
+        ::remove((const char*)tmpfname);
+        if (c & 1)                        // FOXPRO format
+          tmpfname.ext("cdx");
+        if (c & 4)                        // DBIV format
+          tmpfname.ext("mdx");
+        if (c & 8 || c & 2)
+        {                   
+          tmpfname.ext("cgp");
+          char in[16];    
+          FILE *fp=fopen((const char *) tmpfname,"r");
+          while (fgets(in,16,fp)!=NULL)
+          {
+            TFilename a(in);          
+            a.rtrim(1); // Cut \n
+            if (c & 8)                    // DBIII format
+              a.ext("ndx");
+            else
+              a.ext("ntx");       // CLIPPER format
+            ::remove((const char *)a);
+          }
+          fclose(fp);
+        }
+        ::remove((const char*)tmpfname);            
+        dir.eod() = ni;
       }
-      ::remove((const char*)tmpfname);            
-      dir.eod() = ni;
     }
+    dir.set_len(lenr);
+    dir.put(num(), _nordir, _sysdirop);
+    newrec.put(num());
+    if (toconvert && dir.eox() > 0L) packindex();
+    exec_convapp(lev, FALSE);            
   }
-  dir.set_len(lenr);
-  dir.put(num(), _nordir, _sysdirop);
-  newrec.put(num());
-  if (toconvert && dir.eox() > 0L) packindex();
-  exec_convapp(lev, FALSE);            
   setstatus(err);
   return err;
 }
@@ -1647,7 +1654,8 @@ int TSystemisamfile::packfile(bool vis)
   int err=NOERR;  
   TDir d;
   
-  d.get(num());
+  d.get(num(),_nolock, _nordir,_sysdirop);
+  d.get(num(),_nolock, (d.is_com()) ? _comdir : _nordir);
   CHECKS(filehnd() == NULL, "Can't pack open file", (const char*)filename());
   err=DB_packfile(vis,d.name(),d.eod());
   if (err != NOERR) err = get_error(err);
@@ -1668,7 +1676,8 @@ int TSystemisamfile::packindex(bool vis)
   CHECKS(filehnd() == NULL, "Can't pack index of open file", (const char*)filename());
   
   r.get(num());                
-  d.get(num());
+  d.get(num(),_nolock, _nordir,_sysdirop);
+  d.get(num(),_nolock, (d.is_com()) ? _comdir : _nordir);
   err=DB_packindex(vis,d.name(),r.rec(),&peod);
   if (err != NOERR) err = get_error(err);
   if (err != NOERR) error_box("Errore in compattamento indici.\nFile %d : %d", num(),err);
@@ -1676,7 +1685,7 @@ int TSystemisamfile::packindex(bool vis)
     if (peod >= 0 && peod != d.eod())
     {
       d.eod() = peod;
-      d.put(num());
+      d.put(num(),(d.is_com() ? _comdir : _nordir));
     }
   setstatus(err);
   return err;
@@ -1998,7 +2007,7 @@ TRectype::TRectype(int logicnum) : _cod(NULL)
   {
     TDir wdir;
     wdir.get(_logicnum, _nolock, _nordir, _sysdirop);
-    if (wdir.name()[0] == '%')
+    if (wdir.is_com())
       wdir.get(_logicnum, _nolock, _comdir, _sysdirop);
     _length = wdir.len();
   }                                                                               
@@ -2017,7 +2026,7 @@ TRectype::TRectype(const TBaseisamfile* i): _cod(NULL)
     TDir wdir;
 
     wdir.get(_logicnum, _nolock, _nordir, _sysdirop);
-    if (wdir.name()[0] == '%')
+    if (wdir.is_com())
       wdir.get(_logicnum, _nolock, _comdir, _sysdirop);
     _length = wdir.len();
   }