SyncML®: Synchronizing and Managing Your Mobile Data By Uwe Hansmann, Riku Mettälä, Apratim Purakayastha, Peter Thompson, Phillipe Kahn
Table of Contents
Chapter 6. Representation Protocol
The Representation Protocol also defines a set of Static Conformance Requirements (SCR) tables. These tables define what a product is required to support. The tables also indicate optional commands or Elements. Here is an example from the SCR tables:
Support of Synchronization Server
Support of Synchronization Client
This example is from the Common Use Elements section of the SCR tables. For a Server, the Chal command is required for sending and receiving. However, for a Client, it is only required to receive the Chal command.
According to the RFC 2119, MAY indicates entirely optional, SHOULD indicates strongly suggested (i.e. a good technical reason for not implementing), and MUST indicates required.