Compare the contents of this CXlConstCell with another cell
int operator <( const CXlOperBase& xlo ) const;
A reference to another CXlCell, CXlConstCell or CXlOper.
Returns TRUE if the value in this object is less than that in xlo; returns FALSE otherwise.
Note that CXlOpers are sorted by type first and then value. Thus a string containing "123" will not necessarily sort later than an integer containing 122. For CXlOpers of the same type, sort order is always by value.