The text field above accepts catalog numbers or number ranges separated by commas or white space. To get all 1915 to 1920 overprints as listed in the Scott Catalogue type “235-308” (no white space between hyphen and numbers!), “RA1-46, RAC1-23” for all postal tax stamps or “914A-G” for the 1999 Christmas issue. Note that this range notation doesn’t cover subnumbers like “a”, “b”, “c” varieties.