Need to fix invalid cross-references in the specification

In reviewing the current specification and its source, there are several `<>` type of references that seem to be from the old framemaker version of the spec that have not been properly ported or defined. I'll create a PR for some of the ones I ran into, but we should have a list of the invalid cross references and fix them. I'll look to see if there is a way to capture the unresolved cross references from the asciidoc plugin.

Start by reviewing the current specification and its source, then investigate whether the Asciidoc plugin can capture unresolved cross-references. The work is done when the invalid references are listed and the affected references are corrected or properly defined.

Written by the indexing model from the issue text.