...
SIP Model is an abstract model that has to be followed by any PAIS compliant SIP.
Source:Consultative Committee on Space Data Systems. Producer-Archive Interface Specification (PAIS) - A Tutorial. Report Concerning Space Data System Standards, CCSDS 651.2-G-1. Green Book. Issue 1. Washington, D.C.: CCSDS, September 2016. [Equivalent to ISO 20104:2015]
Introduction
...
PAIS provides an abstract SIP Specification (CCSD0017) known as the SIP Model. The SIP Model puts constraints on all possible SIPs within a given Producer-Archive Project.
...
There are two methods by which a Producer-Archive Project can achieve SIPs that conform to the PAIS SIP Model:
Adopt the PAIS SIP Model XML schema based on the XFDU packaging standard (available in the Data Archive Ingest XML repository)
Other Create a specialized SIP Model based on other packaging mechanisms (e.g., the BagIt specification)
...