I looked up OBJNUM() and _CUROBJ and I had the syntax right, it just didn't work. Here's an example of my code:

@ 3,29 GET staff.number ;
SIZE 1.000,13.167 ;
VALID valstaf() error errmess

READ valid valme()

procedure valstaf
ret = .t.
getno = _CUROBJ
if ";"$staff.number
errmess="Person's # may not contain semi-colon(;)"
ret = .f.
endif
return ret

procedure valme
ret = .t.
if "" = trim(staff.number) .and. fromhere <> 2
errmess="Person's # may not be blank"
ret=.f.
wait window errmess nowait
_CUROBJ = getno
else
ret = .t.
if (""= trim(staff.number) .or. isnew) .and. fromhere = 2
delete
endif
endif
return ret