one of the documented procedures in this installation of the ACS
fs_check_read_p   db   user_id   version_id   { group_id "" }
What it does:
Returns 1 if the user can read the version of the file; 0 otherwise.
Defined in: /web/philip/tcl/file-storage-defs.tcl

Source code:

    # see if the user is the owner.  If not, see if the user has permission
    if {[database_to_tcl_string $db "select count(fs_files.file_id) from fs_files, fs_versions_latest where fs_files.file_id = fs_versions_latest.file_id and fs_files.owner_id = $user_id and version_id = $version_id"] > 0} {
	return 1
    } else {
	return [ad_user_has_row_permission_p $db $user_id "read" $version_id "FS_VERSIONS"]