allow start/end rank for dot and svg

diff --git a/script/make_tradition.pl b/script/make_tradition.pl
index 908500d..16d8519 100755 (executable)
--- a/script/make_tradition.pl
+++ b/script/make_tradition.pl
@@ -57,8 +57,8 @@ unless( $outformat =~ /^(graphml|svg|dot|stemma|csv|db)$/ ) {
 }
 
 if( $from || $to ) {
-       help( "Subgraphs only supported in GraphML format" ) 
-               unless $outformat eq 'graphml';
+       help( "Subgraphs only supported in GraphML, dot, or SVG format" ) 
+               unless $outformat =~ /^(graphml|dot|svg)$/;
 }
 
 # Do we have a base if we need it?