I guess I’ve managed to read over the very first line in the apparatus of Rahlf’s text of Genesis for years without ever stopping to make sense of exactly what it says. Some of it (I think!) I know what means, but other parts are opaque to me. I’d appreciate any correction or supplementation. The apparatus at the very beginning of Genesis reads [I'm using ( ) to mark smaller text in Rahlfs; these are verse numbers.]:
Gen.: 1—46(28) ηρωων A, 46(28) πολιν — 50 BA, 23(19)—24(46) (mutila) etiam S.
What I think this says is that Gen 1:1–46:28 is in poetry in manuscript A. (That may be totally wrong; I don’t know exactly what Greek word ηρωων is.) I think the verse references and manuscripts are obvious.
From 46:28–ch. 50 is πολιν (???) in manuscripts B and A, but 23:19–24:46 is mutilated (missing? or just damaged/incomplete leaves?); also manuscript S.
If my guess of “poetry” is correct for ηρωων (and I don’t know that it is), then πολιν is puzzling. (I’d normally take it as a form of πολις, city.)