from what manuscript are you working?
codex Laurentianus Plut.69.35 - written 1101-1200 CE (12 century CE)
http://mss.bmlonline.it/s.aspx?Id=AWOItZA2I1A4r7GxMME1&c=Laertius%20Diogenes#/oro/496
Principal Doctrines start on folio 243v, 10 lines from the bottom on the left side.
The oldest I could find.
And is there more than one which we can compare?
Oh, yeah. There are at least 3 more I want to look at that have no numbers. Plus there are the Latin translations. I've only just started!