Repost: Can $D400-$DFFF in LC Bank2 considered free under ProDOS 8 ?

[Oliver Schmidt <ol.sc@web.de>]

Hi,

I know that the ProDOS8 TechRefMan states that this area is reserved
for future use. But looking back from about 20 years later it should
now be possible to know if it was ever used, shouldn't it?

What I already did was to check that both the "old" quit code (ProDOS
1.7) and the "new" quit code (ProDOS 2.0.3) only seem to occupy
$D100-$D3FF. At least the copy routine that moves the quit code to
$1000 copies in both cases the same area.

So from my current understanding I'd say that a plain vanilla ProDOS 8
never used the area in question. But are there popular / must-have
additions (probably third-party) that use the area?

BTW: I'm planning to use that area for storing ProDOS file buffers.
Those 1k buffers with page alignment requirements are really giving me
a hard time. So I recently came up with the idea to define a memory
area not actually used while doing file i/o (like i.e. $0800-$0BFF)
and to write a little memory exchange routine that temporarily moves a
file buffer out of LC Bank 2 to $0800 prior to the MLI call and back
after returning from the call. The original data at $0800 is stored in
the LC in the meanwhile. That approach would give me three
simultanious open files. Does this make sense? Is it probably even a
popular technique?

Thanks in advance for hints and infos, Oliver