Is =concatenate("a",,a) valid?

[Helmut Wollmersdorfer <helmut wollmersdorfer gmx at>]

On my tries to improve the Gnumeric testcases and compare them with the 
behaviour of MS/XL I got some crazy characters, which seems to be the 
content of a buffer or stack out of XL XP, after entering

  =concatenate("a",,a)

As I understand the docs, the parameter

   a

is not a valid string, or something else valid, and this should always 
result in an error. Right?

Helmut Wollmersdorfer