--- loncom/interface/spreadsheet/Spreadsheet.pm	2004/02/24 20:47:14	1.36
+++ loncom/interface/spreadsheet/Spreadsheet.pm	2005/04/21 17:30:24	1.37.2.1
@@ -1,5 +1,5 @@
 #
-# $Id: Spreadsheet.pm,v 1.36 2004/02/24 20:47:14 matthew Exp $
+# $Id: Spreadsheet.pm,v 1.37.2.1 2005/04/21 17:30:24 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -911,7 +911,8 @@ sub sett {
             $t{$cell}=~s/(^|[^\"\'])([A-Za-z]\d+)/$1\$sheet_values\{\'$2\'\}/g;
             $t{$cell}=~s/(^|[^\"\'])\[([^\]]+)\]/$1.$self->expandnamed($2)/ge;
         } elsif  ( $col  =~ /^[A-Z]$/  ) {
-            if ($formula !~ /^\!/ && exists($self->{'constants'}->{$cell})) {
+            if ($formula !~ /^\!/ && exists($self->{'constants'}->{$cell})
+		&& $self->{'constants'}->{$cell} ne '') {
                 my $data = $self->{'constants'}->{$cell};
                 $t{$cell} = $data;
             }
@@ -1294,7 +1295,7 @@ sub html_editable_cell {
     } elsif ($value =~ /^\s*$/ ) {
         $value = '<font color="'.$bgcolor.'">#</font>';
     } else {
-        $value = &HTML::Entities::encode($value) if ($value !~/&nbsp;/);
+        $value = &HTML::Entities::encode($value,'<>&"') if ($value !~/&nbsp;/);
     }
     return $value if (! $allowed);
     #
@@ -1317,7 +1318,7 @@ sub html_editable_cell {
 sub html_uneditable_cell {
     my ($cell,$bgcolor) = @_;
     my $value = (defined($cell) ? $cell->{'value'} : '');
-    $value = &HTML::Entities::encode($value) if ($value !~/&nbsp;/);
+    $value = &HTML::Entities::encode($value,'<>&"') if ($value !~/&nbsp;/);
     return '&nbsp;'.$value.'&nbsp;';
 }