Review all lowercase usages of RFC2119 keywords, change to uppercase as required

[Technical-DSB]

Description
Where the use of a keyword refers to its meaning under RFC2119, update to use uppercase.

[nils-work]

Related to this issue in Standards Maintenance -

• #473 - Add RFC8174 to list of normative references and update the use of Requirements Levels

[nils-work]

The following changes should be made:

Items included as part of #472:

• Apply bold to existing upper case keywords:
  • MUST [NOT] --> MUST [NOT]
  • SHOULD [NOT] --> SHOULD [NOT]
• Replace 'data holder' and 'register' in the respective x-v and x-min-v header statements with 'endpoint' to make it a common statement. e.g.,:
  • "The data holder SHOULD" --> "The endpoint SHOULD"
  • "The Register SHOULD" --> "The endpoint SHOULD"
• Bold, uppercase 'MUST' in the following sentence (x-fapi-interaction-id Response Header):

  An [RFC4122] UUID used as a correlation id. If provided, the data holder must play back this value in the x-fapi-interaction-id response header. If not provided a [RFC4122] UUID value is required to be provided in the response header to track the interaction.

Items remaining:

• Review usage in the HTTP Headers section.
• Bold, uppercase 'Must' and 'should' in the following sentence (x-v header)

  Version of the API endpoint requested by the client. Must be set to a positive integer. The data holder should respond with the highest supported version between x-min-v and x-v. If the value of x-min-v is equal to or higher than the value of x-v then the x-min-v header should be treated as absent. If all versions requested are not supported then the data holder must respond with a 406 Not Acceptable. See HTTP Headers.

• Bold, uppercase 'Must' and 'should' in the following sentence (x-min-v header)

  Minimum version of the API endpoint requested by the client. Must be set to a positive integer if provided. The data holder should respond with the highest supported version between x-min-v and x-v. If all versions requested are not supported then the data holder must respond with a 406 Not Acceptable.

In Register endpoints

• Bold, uppercase 'Must' and 'should' in the following sentence (x-v header)

  Version of the API endpoint requested by the client. Must be set to a positive integer. The Register should respond with the highest supported version between x-min-v and x-v. If the value of x-min-v is equal to or higher than the value of x-v then the x-min-v header should be treated as absent. If all versions requested are not supported then the Register MUST respond with a 406 Not Acceptable. See HTTP Headers.

• Bold, uppercase 'Must' and 'should' in the following sentence (x-min-v header)

  Minimum version of the API endpoint requested by the client. Must be set to a positive integer if provided. The Register should respond with the highest supported version between x-min-v and x-v. If all versions requested are not supported then the Register MUST respond with a 406 Not Acceptable.

In Get Data Holder Statuses

• Bold, uppercase 'Must' in the following sentence (x-v header)

  The version of the API endpoint requested by the client. Must be set to a positive integer. For backwards compatiblity defaults to 1 if absent. Note that once version 1 is decommissioned the header will be mandatory for a valid response to be obtained.

• Bold, uppercase 'Must' in the following sentence (x-min-v header)

  The minimum version of the API endpoint requested by the client. Must be set to a positive integer if provided.

In Metadata Update and Get Metrics endpoints
The final 'should' in these sentences will also be changed to 'MUST' for consistency with other endpoints.

• Bold, uppercase 'Must' and 'should' in the following sentence (x-v header).

  Version of the API endpoint requested by the client. Must be set to a positive integer. The data holder should respond with the highest supported version between x-min-v and x-v. If the value of x-min-v is equal to or higher than the value of x-v then the x-min-v header should be treated as absent. If all versions requested are not supported then the data holder should MUST respond with a 406 Not Acceptable. See HTTP Headers.

• Bold, uppercase 'Must' and 'should' in the following sentence (x-min-v header).

  Minimum version of the API endpoint requested by the client. Must be set to a positive integer if provided. The data holder should respond with the highest supported version between x-min-v and x-v. If all versions requested are not supported then the data holder should MUST respond with a 406 Not Acceptable.