The ContentRevocation property retrieves content revocation information, which is used to revoke licenses for your protected content.
string = IWMDRMProfile.ContentRevocation;
This property takes no parameters.
A String containing the content revocation information.
This property is read-only.
Content owners have the ability to revoke licenses for their own protected files, thereby revoking the content. Content revocation can be initiated only by the content owner with a string retrieved from the ContentRevocation property. This content-revocation string is based on the public and private signing keys for a specific DRM profile. Only content that was protected with that DRM profile is revoked.
The content owner retrieves this string and shares it with the license provider (for example, in an e-mail message or on a floppy disk), who includes the string in all licenses from that point forward, including licenses issued for other content owners. Then, whenever an end user's player opens a license containing this string, licenses for all protected files by the content owner in question are revoked and end users can no longer play the files.
If an end user tries to play one of the revoked packaged files, the license acquisition URL opens because the license is rendered invalid. The content owner and license provider are then responsible for providing information for end users about the content revocation (for example, to help them get new versions of the revoked content). The content owner should then create and use a new DRM profile for protecting content.
Reference: Windows Media Encoder