IRM features were first introduced in Office 2003. The IRM features are divided into two parts, basic IRM features and advanced IRM features.

 

Basic IRM features means consuming IRM protected documents. However, it does not include creating and changing the permissions.

 

Advanced IRM features include:

l          Create IRM-protected documents and e-mail messages.

l          Grant access and editing permissions, and apply policy templates to protected content.

 

In Office 2003, advanced IRM features were only available in Professional and Enterprise Edition.

 

Office 2007 expanded the packaging options from 3 to 8. Among the 8 different packaging options of Microsoft Office 2007 Suit, advanced IRM features are only available in Ultimate, Professional Plus and Enterprise version. Other versions may only consume IRM protected documents.

 

For more details, please check

http://office.microsoft.com/en-us/suites/FX101635841033.aspx