Now reads:

"A section that links to external content contains a full representation of the data, so that consumers need to understand the linking information only if they wish to update the contents of the section."

Two questions:

1) Should the first clause say "A section that links to external content shall/should/may/can contain a full representation of the external content that appears in the section."

???

2) Should the second clause read (as a separate sentence): "Consumers may/can process links to external content to update the external content that appears in a section."

???

Noting that neither consumers nor producers "understand" anything. They apply rules we define. Understanding is not required.