"only printing" and levels

[maximedenes]

I was surprised to see that this is accepted:

Notation "!!" := False (at level 0, only printing).
Notation "!!" := False (at level 1).

while the following is rejected:

Notation "!!" := False (at level 0, only printing).
Notation "!!" := False (at level 1, only printing).

Is it expected?

Cc @herbelin

[herbelin]

This evolved, but apparently not consistently. There have been requests for supporting an arbitrary number of only printing notations at arbitrary levels (thus consciously losing any kind of reversibility of the parsing).

Consistently with these requests, the second one, as well as:

Notation "!!" := False (at level 1).
Notation "!!" := False (at level 0, only printing).

should a priori be accepted (or, at least, they should be accepted if the rhs is a distinct pattern).

Added: and if the rhs is the same pattern, issuing an overriding warning.