Yep, floating heads do exist in documents other than magazines.
This is exactly what we've implemented in our DTD for software
documentation (we got the idea from Bull, which submitted its
"in-between title" idea to OSF for its consideration). We now have a
"bridging title" whose purpose is to help the reader navigate the
discussion once he/she has located it, but which is not meant to label
just the following "region" -- rather, it often bridges the previous
and following discussions.
It does create sort of a phantom region in the mind's eye, and we
realize the idea is tainted with a bit of presentation specificity, but
it buys us certainty that the entire discussion won't be broken up into
tiny little (useless, incomplete) topics in our online book viewer.
We've found the concept to be pretty useful, seems intuitive for
writers to apply, and is a good alternative in places where you want to
*structure* information, just not strongly *hierarchically*. (Clear as
mud? :-) I believe it's been picked up by several of the organizations
who were involved in the OSF conversations.