This function is intended primarily as a means of iterating round all the columns in a Table. For this purpose, the number of columns in the Table is given by the Ncolumn attribute of the Table. This function could then be called in a loop, with the index value going from one to Ncolumn.
Note, the index associated with a column decreases monotonically with the age of the column: the oldest Column in the Table will have index one, and the Column added most recently to the Table will have the largest index.
A blank string will be returned if this function is invoked with STATUS set to an error value, or if it should fail for any reason.