V5.4 SIZE() for undefined variable

[Wayne Landsman <landsman(at)mpb.gsfc.nasa.gov>]

I don't remember seeing it mentioned before that the output of the SIZE
function for undefined variables changed in IDL V5.4.      The last
element of the vector returned by SIZE() for an undefined variable is
now 0 rather than 1.    Since this value is supposed to be the number of
elements in the variable, the V5.4 output makes more sense.     But at
least one astronomical package had taken for granted the previous IDL
behaviour and so had to be updated to be compatible with IDL V5.4.
Cheers, --Wayne

IDL> print,!version
{ sparc sunos unix 5.4 Sep 25 2000      64      64}
IDL> delvar,x
IDL> print,size(x)
           0           0           0

IDL> print,!VERSION
{ sparc sunos unix 5.3 Nov 11 1999}
IDL> delvar,x
IDL> print,size(x)
           0           0           1