--- trunk/IsisDB.pm	2004/12/31 05:43:20	25
+++ trunk/IsisDB.pm	2005/01/01 22:29:35	27
@@ -37,7 +37,8 @@
 =head1 DESCRIPTION
 
 This module will read ISIS databases created by DOS CDS/ISIS, WinIsis or
-IsisMarc. It can be used as perl-only alternative to OpenIsis module.
+IsisMarc. It can be used as perl-only alternative to OpenIsis module which
+seems to depriciate it's old C<XS> bindings for perl.
 
 It can create hash values from data in ISIS database (using C<to_hash>),
 ASCII dump (using C<to_ascii>) or just hash with field names and packed
@@ -50,7 +51,7 @@
 It also has support for identifiers (only if ISIS database is created by
 IsisMarc), see C<to_hash>.
 
-This will module will always be slower than OpenIsis module which use C
+This module will always be slower than OpenIsis module which use C
 library. However, since it's written in perl, it's platform independent (so
 you don't need C compiler), and can be easily modified. I hope that it
 creates data structures which are easier to use than ones created by
@@ -214,11 +215,14 @@
 
 =head2 read_cnt
 
-This function is not really used by module, but can be useful to find info
-about your index (if debugging it for example).
+Read content of C<.CNT> file and return hash containing it.
 
   print Dumper($isis->read_cnt);
 
+This function is not used by module (C<.CNT> files are not required for this
+module to work), but it can be useful to examine your index (while debugging
+for example).
+
 =cut
 
 sub read_cnt  {
@@ -331,7 +335,7 @@
 	# (XRFMFB - 1) * 512 + XRFMFP
 	# why do i have to do XRFMFP % 1024 ?
 
-	my $blk_off = (($XRFMFB - 1) * 512) + ($XRFMFP % 1024);
+	my $blk_off = (($XRFMFB - 1) * 512) + ($XRFMFP % 512);
 
 	print STDERR "## pointer: $pointer XRFMFB: $XRFMFB XRFMFP: $XRFMFP offset: $blk_off\n" if ($self->{'debug'});
 
@@ -345,8 +349,14 @@
 	print STDERR "## offset for rowid $value is $blk_off (blk $XRFMFB off $XRFMFP)\n" if ($self->{debug});
 
 	if ($value!=$mfn) {
-		carp "Error: MFN ".$mfn." not found in MST(".$value.")";    
-		#return;
+		if ($value == 0) {
+			print STDERR "## record $mfn is physically deleted\n" if ($self->{debug});
+			$self->{deleted} = $mfn;
+			return;
+		}
+
+		carp "Error: MFN ".$mfn." not found in MST file, found $value";    
+		return;
 	}
 
 	read($self->{'fileMST'}, $buff, 14);
@@ -414,11 +424,11 @@
 
 =head2 to_ascii
 
-Dump ASCII output of record with specified MFN
+Returns ASCII output of record with specified MFN
 
   print $isis->to_ascii(42);
 
-It outputs something like this:
+This outputs something like this:
 
   210	^aNew York^cNew York University press^dcop. 1988
   990	2140
@@ -455,7 +465,7 @@
 
   my $hash = $isis->to_hash($mfn);
 
-It has ability to convert characters (using C<hash_filter> from ISIS
+It has ability to convert characters (using C<hash_filter>) from ISIS
 database before creating structures enabling character re-mapping or quick
 fix-up of data.
 
@@ -551,7 +561,18 @@
 
 =head1 BUGS
 
-This module has been very lightly tested. Use with caution and report bugs.
+Some parts of CDS/ISIS documentation are not detailed enough to exmplain
+some variations in input databases which has been tested with this module.
+When I was in doubt, I assumed that OpenIsis's implementation was right
+(except for obvious bugs).
+
+However, every effort has been made to test this module with as much
+databases (and programs that create them) as possible.
+
+I would be very greatful for success or failure reports about usage of this
+module with databases from programs other than WinIsis and IsisMarc. I had
+tested this against ouput of one C<isis.dll>-based application, but I don't
+know any details about it's version.
 
 =head1 AUTHOR