Understanding filter priority for more and nextpage tags

I'm trying to understand the exact actions internally to WP of the more and nextpage tags. It seems they transform into a span tag of some kind, but I can't really tell where they're processed in the filter priority and exactly what code is interpreted by what for things like home page themes.

Have you ever seen a detailed explanation of how these things work at the coding level? Right now, they're completely munging my parsing routine and that's really frakin' annoying.

Thanks!