Gets or sets whether the content type can be modified.
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
Available in Sandboxed Solutions: Yes
Available in SharePoint Online
You must have administrative rights to the site collection to unseal and edit a content type that is defined as sealed.
For more information, see Content Type Change Control.
Defining a content type as sealed has ramifications when you make changes to its parent content type and then attempt to propagate those changes down through the hierarchy of content types. For more information, see Updating Child Content Types.