Makefile.am question

[Till Straumann]

I'm in the process of brining my BSP in sync with the latest snapshot's
(auto)make files.

I'm sure this has been asked before:

What is the difference between TMPINSTALL_FILES and PREINSTALL_FILES?

The powerpc/shared/motorola_powerpc BSP who I am using as a reference
seems to make inconsistent (maybe the logic behind it is just too 
obscure for me to guess) use of both of them. Some Makefile.am use
TMPINSTALL_FILES some use PREINSTALL_FILES to get headers installed
into the build area... ??

-- Till.