CDDL doesn't handle null suppression for authority

[thomas-fossati]

The CDDL in the appendix fails to handle null suppression at least in case a null authority is elided:

["a"] (i.e., "a:")

[thomas-fossati]

As discussed, a simple fix would be to remove the CDDL in appendix and tighten the text in Section 5.1 from "Trailing null values are removed, [...]" to "Trailing null values MUST be removed, [...]"

[cabo]

Closed in a303800