HP WBEM Services Software Developer's Kit for HP-UX Provider and Client Developer's Guide A.01

CIM Naming Guidelines
Classes
Appendix A118
Subclassing to Add Properties/Methods
Extending the schema to create a new subclass is also appropriate when
adding properties or methods to a DMTF class. In addition, overriding a
property or method (such as to include the write qualifier on a property)
is also a valid reason to create a subclass.
In these cases, the basepart of the class name would stay the same, so an
ACME-specific subclass of CIM_EthernetPort could be called
ACME_EthernetPort, while the ACME Unix extension to
CIM_OperatingSystem would be ACMEUnix_OperatingSystem.