That is the TIDM, found at http://tess2.uspto.gov/netahtml/tidm.html
These are called classes, not categories. There are some for goods and some for services. There are no "subcategories", that is something that is used in patent classification.
While your promotional essay is informative, I would suggest the Questioner might also view a few of the exceptionally well-done short TMIN videos at http://www.uspto.gov/trademarks/process/TMIN.jsp