I don't add all the film numbering etc when I use census records, I go with ''(link) BAC-LAC, Collections Canada, Recensement (year) Census, district # (name), sub-district (name), page #, lines _ - _. ''. That way the actual pertinent data showing on the record to locate it again is all present. Film numbering and ''individual'' numbering are all subject to change. Computer programmers regularly sell them ''new / improved'' systems. My brother used to work for the government, and I've heard some horror stories of computer disasters over the years.