Networked Media Open Specifications

NMOS Parameter Registers: General Procedures and Criteria

The procedures for updating a parameter register are straightforward.

The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “NOT RECOMMENDED”, “MAY”, and “OPTIONAL” in the defined criteria are to be interpreted as described in RFC2119. Note that the force of these words is confined to the scope of this repository.


A typical example of specific criteria is found in the NMOS Node Service Types parameter register. AMWA IS-04, since v1.1, allows a list of ‘services’ to be advertised on the node resource in the Node API. Each advertised service has a ‘type’ property whose value is a Uniform Resource Name (URN), as well as its ‘href’ property which provides a URL to reach the service. The Node Service Types parameter register provides implementers with the means to discover and disclose service type names (URNs) that are in use.

So, for example, its criteria includes the following statements:

  • Each entry MUST define a unique service type name (which is a URN).
  • Each entry MUST have a short description and include contact information for the proponent(s).
  • Each entry SHOULD provide a link to a specification for the service type, as well as identifying the AMWA IS-04 API Versions for which the entry is applicable.
  • In the case of substantial revision to the service specification, a new service type name MUST be defined. Using versioned names is therefore RECOMMENDED.
  • Additions and updates to this parameter register are to be submitted via a Pull Request (PR) according to the General Procedures and Criteria.

However, modifications to a parameter register may be more closely controlled than this. For example, in the case of the NMOS Formats parameter register, values are defined only by revisions of AMWA IS-04 itself.