Most of what is in the SP7 version, are so that matching can be configured more easily. A lot of them are for MDG as that can be configured more dynamically and not use the traditional Business Address Service for processing but use custom fields. Most users don't end up changing them.
The one that are commonly configured are the ones that are documented. the ones that are there as they are passed from the ABAP side are not as they are configured as IMG settings or other configurable items on the SAP side. so the documentation would provide the insight as to how to configure it in the way that is expected for a SAP users.
The real question, is what problem are you trying to solve that has you looking at the Substitution variables?