Hi,
I guess you could add your own tag. Look at the source in
http://cookbook-1.3.hobocentral.net/api_tag_defs/record-flags for inspiration.
I guess the "where-true" part is achieved via the .select, which picks elements that return true (this.send(f).
Maybe you could extend it with another attribute, that can customize what the record-flags check for (true or false). If your change is lean and makes sense, maybe it even makes it back into rapid.
Regards,
Ronny