To piggy back onto Gary's rub here:
One of the parameters is:
"Only straightforward instruction sheets will be included in this experiment. They include, but are not necessarily limited to the following.
H 1120 Names of families
H 1145.5 Bodies of water
H 1151.5 Types of educational institutions
H 1185 Religions
H 1187 Christian denominations
H 1195 Land vehicles
H 1200 Wars"
I wonder what the status is of this experiment [as Adam notes it is indeed being done, but has the scope changed at all?]
But to add to the general discussion -- what will be challenging in proliferating 072s/073s throughout LCSH is that not every category has an SHM memo to point to.
Consider the following subdivisions:
—Access control (May Subd Geog)
Use as a topical subdivision under types of archives, records, computers, computer networks, and statistical and data-gathering services.
Though it has an 073 for H 1095 [Free-Floating Subdivisions], it's only usable under very specific types of headings, most of which do not have a unique SHM memo to point to.
Use as a topical subdivision under substances, including individual chemicals and groups of chemicals and individual materials and types of materials, and individual plants and groups of plants, for works on methods of analyzing those substances, or analyzing a sample, to determine the presence or quantity of those substances. Also use under substances not produced naturally for works presenting the results of chemical analyses of those substances. For results of chemical analyses of natural substances of unfixed composition, use the subdivision Composition. [Emphasis mine]
Although four memos are listed in the 073 [Free floating subdivisions, Chemicals, Materials, and Plants and crops] how can a programmatic validation match "substance not produced naturally" unless there is a corresponding 072 code that can be added to the LCSH which satisfy that requirement.
The LCDGT vocabulary does this very well, in that every category that a term can belong to is laid out ahead of time and each has their own memo. I think it's ultimately an enumeration problem. Somehow [and I'm obviously not suggesting that this is a practical to task to take on] every possible category that a subdivision refers to needs to be enumerated and assigned a unique code [perhaps with a relevant memo, perhaps not] and then every LCSH would need an 072 for the precise categories to which it belongs -- then our bibliographic utilities would be able to not only control the headings but also validate them.