Leveling Rules for Set Value Expression

1. Support for <desc_flags> other than SELF is optional. Consumers can check the value of the property MDPROP_MDX_SET_FUNCTIONS to see whether a provider supports this feature.
   
   
2. The following set functions are optional: TOPPERCENT, TOPSUM, BOTTOMPERCENT, BOTTOMSUM. Consumers can check the value of the MDPROP_MDX_SET_FUNCTIONS property to see whether a provider supports this feature.
   
   
3. The following set functions are optional: PERIODSTODATE, LASTPERIODS, YTD, QTD, MTD, WTD. Consumers can check the value of the MDPROP_MDX_SET_FUNCTIONS property to see whether a provider supports this feature.
   
   
4. The ability to have expressions containing nonmeasure dimension members in the <numeric_value_expression> argument of set functions. For example, if Revenue and Cost are measures and USA is a member of Geography dimension, then in set functions that take a <numeric_value_expression> argument, the support for expressions such as Revenue/3 and (Revenue - Cost)/Cost*100 are mandatory. However, support for expressions such as (USA, Sales)/3 are optional. Consumers can check the value of the property MDPROP_MDX_NONMEASURE_EXPRESSIONS to see whether a provider supports this feature.