Thanks JC!
Well, therein lies my problem: I don't have a page 170 onward in my manual that came with distribution. Mine only goes to page 167. My manual has very broad definitions of tags, but no specifics - like "so-and-so tag will reset to zero at midnight", etc.
Your STAT$RAIN:TOTAL:TODAY$ tag looks like it fits my needs, though, thank you very much! Does it reset to zero at midnight?