How additional attributes extend the data model
If an existing class describes your configuration item (CI) well but lacks a few pieces of information, add attributes to the existing class to store that information and avoid the performance cost of a subclass. To store some CIs that use these attributes and some that do not, make the entry mode of the attributes Optional.
Adding attributes works well when you have only one variation on a class to accommodate. If you have two or more variations, each with their own set of attributes, consider creating subclasses for them instead.
Before creating an attribute for a CI class, determine whether you want to store configuration data or lifecycle data for the CI in the new attribute. You must create a new attribute to store only configuration data for the CI. To store lifecycle data for the CI, you must add a field on the BMC Remedy ITSM Foundational form, AST:Attributes.
If you decide to add attributes, follow the Field ID rule in Naming and numbering rules for new classes and attributes.
When you add attributes to your data model, the new attributes are not automatically picked up by BMC Software products that use BMC Atrium Configuration Management Database (BMC Atrium CMDB), such as BMC Impact Solutions or BMC Asset Management. To use the new attributes with one of these applications, you must customize the application. For more information, see Making data model changes visible to applications.