There are many reasons for creating or modifying subjects, metaclasses and properties. For example, you might be using an unsupported OS, compiler (configuration), or configuration management tool.
When creating a subject, you can keep existing metaclasses and properties intact. For example, the OMUContainers, OMContainers, and STLContainers subjects are all different subjects which contain the same metaclasses and properties.
Likewise, when creating a metaclass, you can keep existing subjects and properties intact. You can also create new properties under existing subjects and metaclasses. For example, if you were using a testing tool that Rational Rhapsody did not support, you might create new properties under an existing metaclass.
You can create new metaclasses and properties using existing Rational Rhapsody properties.
For example, to add a new configuration management tool to Rational Rhapsody: