It looks like if the input tiddlers don't have the field in question it will return them all. if you add has[length] than that may help.
I am not sure that these filters actually work well, they were an experiment that I made a while ago so I don't remember much about the code. -- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/tiddlywiki. To view this discussion on the web visit https://groups.google.com/d/msgid/tiddlywiki/367fd220-8a8b-4481-9e53-374e348b691a%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.

