Review identifier scoping and uniqueness documentation

[david-waltermire]

User Story:

As an OSCAL content creator and consumer, I need clear guidance on the scope and uniqueness of identifiers used within the OSCAL models.

Goals:

• Generate a list of identifiers used in the OSCAL models
• Review model documentation related to these identifiers to ensure their scoping and uniqueness is clearly stated.
• Add constraints to enforce uniqueness where possible.

Dependencies:

{Describe any previous issues or related work that must be completed to start or complete this issue.}

Acceptance Criteria

• All OSCAL website and readme documentation affected by the changes in this issue have been updated. Changes to the OSCAL website can be made in the docs/content directory of your branch.
• A Pull Request (PR) is submitted that fully addresses the goals of this User Story. This issue is referenced in the PR.
• The CI-CD build process runs without any reported errors on the PR. This can be confirmed by reviewing that all checks have passed in the PR.

[Rene2mt]

Please see changes on my fork (Rene2mt@92c7a95). If all looks okay, I'll do a PR.

[david-waltermire]

This is addressed by PR #860, which still needs some work to get the text right.

[Rene2mt]

Changes completed (see PR#941), however, seeing conflict on the PR that needs to be resolved.

[Rene2mt]

• Created a new documentation page under "Concepts" that provides a summary narrative on identifier use, including the most common identifier types in OSCAL, their uniqueness, and scope. This documentation also attempts to describe which identifiers may be referenced when an OSCAL document imports another (e.g., AP imports SSP).
• All Metaschemas have ben updated (pending review - see Identifier Scoping and Uniqueness Documentation Review #1066 ).
• WIP: html anchor links from Metaschemas documentation to identifier use page. This has been added one a few of the control layer Metaschemas . To review, run the build tools (generates OSCAL XML and JSON) and then generate model documentation (creates all the reference docs).