"as described above" should be accompanied by a link

[mgeier]

Or it should be told in some other way where to look.

Otherwise, it isn't really helpful. Because there's a lot of stuff "above"!

There are three occurrences, two of them right next to each other.

Just before http://spec.commonmark.org/0.27/#link-reference-definitions:

The exception is inside <pre> tags, but as described above, raw HTML blocks starting with <pre> can contain blank lines.

In http://spec.commonmark.org/0.27/#inline-link:

The link’s URI consists of the link destination, excluding enclosing <...> if present, with backslash-escapes in effect as described above. The link’s title consists of the link title, excluding its enclosing delimiters, with backslash-escapes in effect as described above.

[jgm]

Agreed, these should be made into links whenever possible.