foobar B13 won't guess tags from filename, or at least not from wav files. the error message says the file is unsupported or corrupt, but B13 will play the file just fine. i have to use foobar v.8 to guess the tags, and i use the same exact script for the guessing and it works.

I don't know, but I suspect that it is the writing of the tags that is the issue, and not the parsing of the filename.

It seems to me that 0.9 is being more strict about standards, and I can image that it will not tag WAVE files, unlike 0.8.

In fact, I've just tried tagging a WAVE file and got the message:

Just to clear up a misconception: the syntax used for the pattern in "Guess from X" is not that of the title formatting language.

Anyway, your problem with .WAV files is that they do not support tagging, so the error message tells you that foobar2000 cannot write tags to the files. 0.8.3 couldn't write tags to those files either, but it would silently update its cached metadata without telling you about the problem.

See this post for differences regarding tag writing in 0.8.3 and 0.9.

i see! well that explains it. thank you.