Essbase user-defined attributes (UDAs), attributes, and attribute dimensions surface in MDX as member properties and additional dimensions available to the cube. There are some similarities to and some differences from the Microsoft UDM model of attributes in dimensions. This chapter covers how to reference and use the Essbase attributes and dimensions through MDX.
First, we will recap the difference between UDAs and other attributes, then describe attribute dimensions, and finally look at the ways of using them in MDX.
Essbase supports two different kinds of attributes, one called UDAs (for historical reasons) and one called simply "attributes." A UDA is just a name, the presence or absence of which is essentially a Boolean flag that can be associated with any member anywhere in the hierarchy from any regular dimension, and many members (even across different dimensions) can share the same UDA. You can associate UDAs with measures/accounts as well as with other members. Several different UDAs can be associated with a member simultaneously. This makes them useful for identifying related groups of members for application purposes.
An attribute is more similar to an attribute in the data warehousing sense. Values for an attribute are collected in an attribute dimension, which may form a single hierarchy with a leaf level, a hierarchy root member, and perhaps other attribute members in between ...