Issues with drop of a scalar argument

[Kacper Gutowski]

1° With left argument longer than one, the scalar is properly 
extended to a higher rank one-element array, but then it's not 
dropped correctly unless all axes are non-zero.

      ⊢X← 1 0↓2
2
      ⍴X
1 1

The X here should be an empty array (0 1⍴0) but is (1 1⍴2). 


2° When left argument has one non-zero element and right is 
a non-zero scalar, the returned result is a weird value that 
looks like the correct one (0⍴0), but is distinct, and isn't 
transferable.

      8⎕CR Y← 1↓1
┌⊖┐
│0│
└─┘
      ⍬≡Y ⍝ should be true
0
      (11⎕CR⍬)≡(11⎕CR Y)
1
      Y ≡ 12⎕CR 11⎕CR Y
0


3° This might not be an error, but I find it surprising:

      3 ≡ ''↓3  ⍝ this is correct
1
      ''↓⍳3  ⍝ this is an extension (length error by ISO)
2 3
      ''↓⍳3 3
LENGTH ERROR
      ''↓⍳3 3
      ^  ^

By my reading of ISO, when left argument is empty, the right 
must be a scalar (or it will be a length error) which is 
returned unchanged.  In Dyalog it's extended such that any 
value is returned unchanged, in GNU APL ⍬↓X ←→ 1↓X for 
non-scalar X.  Is this intended and correct?  (Is that what 
APL2 does?)

-k