This function is only available when connected to a Teradata database.
An Expand Column Reference can be used to reference the alias of an Expand On expansion period, as described in Variable Creation - INPUT - Expert Options - SQL Elements. An Expand Column Reference can be used in the definition of a Variable or in an ORDER BY expert clause, but not in a Dimension, join clause search condition, subquery or expert clause other than ORDER BY. It may also not appear in an Aggregate or Ordered Analytical function.
There are no special properties for the Expand Column Reference SQL element. It is not necessary for the user to provide the value of the Expand Column Alias here; it is taken automatically from the Expand On expert clause (which must, however, exist if an Expand Column Reference is used).