2.8 System and Registry URL
SData reserves the following URLs for “system” resources and services:
The $system segment name is reserved by SData. At this stage, SData only defines the registy segment below it, for the registry service. See SData Registry section for details.
Other system services similar to the registry may be introduced in the future. They will all be rooted at the $system URL. The $system URL space is reserved for standard SData services. Applications should not introduce non standard segments under $system, unless they prefix them with an underscore. See Extensibility section.
SData providers MAY support the $system URL and implement the registry contract. If they do so, their $system URL MUST be under the /sdata virtual directory.