# Appendix 4.A Prior Art

_Peios / Advanced Peios / PCDS / SID_

> The SID derives from MS-DTYP §2.4.2, keeping both the packet encoding and the S-R-I-S string convention.

## 4.A.1 MS-DTYP

The SID type defined in this document derives from the Microsoft
Data Types specification (MS-DTYP), §2.4.2. The Peios binary
encoding is identical to the MS-DTYP packet representation, and the
string form follows the same `S-R-I-S` convention. The structure
itself originates in Windows NT, where it has been the principal
identity primitive since NT 3.1.