To cut down on the time invested to locate files, the tex4ht.c program maintains a bookkeeping file where it records the addresses of the files it finds. Whenever the program needs to locate a file, it first searches the address in the bookkeeping file. If it doesn’t find the address there, the program embarks on a search throughout the physical directories of its platform.
The program places the bookkeeping file at the first applicable location of the following list.
The bookkeeping file must have writable access mode, and the directory which contains the file should have a compatible access mode.
The bookkeeping file is a dynamically constructed variant of the ls-R file of kpathsea. TeX4ht ignores its own bookkeeping mechanism, if the program tex4ht.c is compiled with a raised -DKPATHSEA switch.