The function returns an invalid value, in objRef is
the reference to an unknown object or the object is other type than Structured
variable or Structure definition.
Moreover, it returns an invalid value, if the value of col is out of
range, which is defined by the number of columns of the particular object.
If the function returns the empty string, the column is not associated with
the display mask.
Example
RECORD (SD.Struct)_rec
TEXT _tTransPalMask
_tTransPalMask := %GetItemTransPalMask(SD.Struct\HBJ, 1)
_tTransPalMask := %GetItemTransPalMask(SV.Struct\HBJ, 3)
_tTransPalMask := %GetItemTransPalMask(_rec\HBJ, 2)