Since enhancement package 1 of CRM7.0, the following four set types were delivered for use by the AET extensibility tool. As a result they were added to black list in subroutine OKCODE_1000 (FuGr COM_ATTRIBUTE_NEW) to suppress generation by transaction COMM_ATTRSET. If you look into table COMC_SETTYPE and COMC_SETTYP_ATTR, the entries are there like other set types generated by COMM_ATTRSET.
Later, probably, the following two set types were delivered as well.
When new field is created by the AET tool for product object, e.g. object part, the field will be added into the set type (table COMC_SETTYP_ATTR) and corresponding Data Source (BW extractor) if the field is marked as BW relevant in AET tool, e.g. 0CRM_CRM_EXT_MAT_ATTR, automatically. The complete Data Source list is as following.
The above Data Sources were generated by report COM_DS_GENERATE_SETTYPE for the corresponding set type. The following program were generated at same time. The report will populate table COMC_CRD_GEN_BWO with an entry for a set type when generating Data Source.