Numbering Quire and pages

[-JKP-]

My post supports the abbreviated "us" ending and showed a list of pope reign dates that not only share the exact use of "pm9" (primus) (#6 & #8 below) meaning "first", but shows some other similarities with the text, namely "cc" and "40". I was postulating that "m9" represents medius, meaning middle, "t9" terminus, meaning end, and "89" maybe penultimate?

The cc and 4o are also consistent with 15th-century Latin abbreviations, as is usqz (usquibus).

The cc ligature had various meanings (again, depending on context), including cc, cr, ci, tc, tr, etc. Sometimes you can't tell which one it is without reading the rest of the word (and sometimes the rest of the words around it—the shape doesn't always tell you exactly which letters they are (or whether they are numbers rather than letters). In medieval Latin, interpretation is based on context.

The 4o was often used as an abbreviation for quarto, just as 8o is octavo. It was uncommon to use the modern "4" shape until the later 15th century (the EVA-l character was used rather than the "4" we use now) but I have examples from the early 15th century and even some from the 14th century.

And yes p'm9 is primus.