Important variables that are not customization items:
This is an alist of the form:
(("/src/dir/0" . tag-hash0) ("/src/dir/1" tag-hash1) … )
Each tag hash entry then contains entries of the form:
"tag_string" => (("file/name.ext" line char) … )
i.e., an alist mapping (relative) file paths to line and character offsets.
hfy-tags-rmap is an alist of the form:
(("/src/dir" . tag-rmap-hash))
Where tag-rmap-hash has entries of the form:
"tag_string" => ( "file/name.ext" line char )
Unlike hfy-tags-cache these are the locations of occurrences of tagged items, not the locations of their definitions.
hfy-tags-sortl is an alist of the form:
(("/src/dir" . (tag0 tag1 tag2)) … )
Where the tags are stored in descending order of length.