The Chamber Music Conference and Composers’ Forum of the East (informally known as the Bennington Music Camp) has kindly published a list of standard rules for measure numbering. Thank you!
Also, buried in that text is a link to a .pdf file listing the last measure numbers of many, many works – this is where we get the last measure numbers for the WOWs. It’s very useful to keep a copy of the file on your computer.
NOTE: Presently there’s a problem with Bennington’s .pdf file that’s posted on their site, which has lost 2/3 of its pages. I’ve contacted Bennington to try to resolve this. Meanwhile, please contact me if you need a copy of the original file. firstname.lastname@example.org