I was picking tomatoes in the garden when I thought about telling Carol (my wife) the plants are about to stop producing.
Those plants are at a particular address, in the backyard, middle garden bed of three, are of three different varieties, but I am going to sum up those properties by saying: “The tomatoes are about to stop producing.”
It occurred to me that a subjectIdentifier could be assigned to a topic element on the basis of summing up properties of the topic.* That would have the advantage of enabling merging on the basis of subjectIdentifiers as opposed to more complex tests upon properties of a topic.
Disclosure of the basis for assignment of a subjectIdentifier is an interesting question.
It could be that a service wishes to produce subjectIdentifiers and index information based upon complex property measures, producing for consumption, the subjectIdentifiers and merge-capable indexes on one or more information sets. The basis for merging being the competitive edge offered by the service.
If promoting merging with a vendor’s process or format, which is seeking to become the TCP/IP of some area, the basis for merging and tools to assist with it will be supplied.
Or if you are an intelligence agency and you want an inward and outward facing interface that promotes merging of information but does not disclose your internal basis for identification, variants of this technique may be of interest.
*The notion of summing up imposes no prior constraints on the tests used or the location of the information subjected to those tests.