Not really a very important function. Just lets you change the name and file owner of a standard SPECX-format data file, but since these are purely informative, and are not used by the operating system, there is rarely any urgency to correct them.
Examples:
>> edit-file-header<CR>
File number? (^z to list) [1] <CR>
New file title? [test] dummy<CR>
New file owner? [me] rachael<CR>