A. Server 2008 R2 updated the basic sharing dialog, as shown below. It no longer has the Co-Owner and Contributor options. Read/Write is the equivalent of Contributor, but Co-Owner is no longer represented. If you want to give a user Full Control, you need to use the Advanced Sharing option, which allows assignment of Full Control permissions.

Click to expand.

As a side note, in my testing with Server 2008 R2 permissions, I found that changes you make with the basic sharing dialog don't seem to actually take effect, making the dialog fairly worthless in the release to manufacturing version of the OS.

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