a2e1730f_olap4j_Specification__Description
[Column name] Zero or more additional columns [Type] int [Description] 
No properties are returned if the members could be returned from multiple levels. For example, if the Tree operator is PARENT and SELF for a non-parent child hierarchy, no member properties are returned. This applies to ragged hierarchies where tree operators could return members from different levels (for example, if the prior level contains holes and parent on members is requested).
olap4j Specification