The default mechanism for creating search strings and for doing the actual search related to a file link may not work correctly in all cases. For example, BibTeX database files have many entries like ‘year="1993"’ which would not result in good search strings, because the only unique identification for a BibTeX entry is the citation key.
If
you come across such a problem, you can write custom functions to
set the right search string for a particular file type, and to do
the search for the string in the file. Using
add-hook, these functions need to be added to the
hook variables org-create-file-search-functions and
org-execute-file-search-functions. See the docstring
for these variables for more information. Org actually uses this
mechanism for BibTeX database files, and you can use the
corresponding code as an implementation example. See the file
org-bibtex.el.