Wow, thanks it works great, it took just a couple of minutes to sort through 1,200 Pdfs. I had to create the destination folders first in C:\PDF
I'd been trying to find a solution from XP's command prompt but not having much success.
I afterwards came across the util (copyright 2000, cooltools), xmove.exe, which uses the syntax
XMOVE source_dir file_pattern destination_dir [modifiers]
by using the wildcard * before a word, after a word and either side of the word, all files whose filename contains that word can be moved to another folder:
xmove C:\PDF math* C:\MATH
xmove C:\PDF *math C:\MATH
xmove C:\PDF *math* C:\MATH
Whether copy, move, xcopy, xxcopy, robocopy have a similar ability to deal with wildcards, I'm not sure.