This read-only integer reports, from a host PDU, the total number of PDU identification entries available across the whole daisy chain, while a slave PDU only ever reports 1. An admin uses it to know how many identification rows to expect before walking the ePDU2Ident table for serial numbers and model info. For example, a host reporting 4 tells the admin there are four physically chained PDUs to identify, not just the one being queried.