Filkbooks are indeed lyrics & chords and sometimes sheet music collections, not articles about filk. Which may be why they're not often called "zines." (Or at least, not that I've heard.) But they're certainly treated like other zines, both in practice and on the meta-levels: they can be multifandom or single-fandom, one author or many (many's a lot lot more common), a dozen pages stapled & handed around or high-quality printer productions, and so on.
The 'zine category and sorting works for them; it's just skewed in favor of "fic zines are the normal fanwork; filkbooks are the variation." I don't see an easy way around this, unless filkbooks get separated out entirely from zines. (Which might be the thing to do.)
There are definitely enough filkbooks to be worth a subcategory. There's nowhere near as many as fic zines, but there are many conventions that have the official (or at least authorized) filkbook for that con.
Yeah, anthologies with filk are not "filkbooks" any more than anthologies with art are portfolios or galleries.
Re: speaking of filkbooks
The 'zine category and sorting works for them; it's just skewed in favor of "fic zines are the normal fanwork; filkbooks are the variation." I don't see an easy way around this, unless filkbooks get separated out entirely from zines. (Which might be the thing to do.)
There are definitely enough filkbooks to be worth a subcategory. There's nowhere near as many as fic zines, but there are many conventions that have the official (or at least authorized) filkbook for that con.
Yeah, anthologies with filk are not "filkbooks" any more than anthologies with art are portfolios or galleries.