Why can't I edit an event sent thru Exchange meeting invites from others?

Is there any way to edit an Event in iOS 6 when it is sent from others as an Invitation? I don't see the Edit button in the upper right of the screen for invitations sent by others on our Exchange network (Exchange 2003 & 2010 mixed environment).

I do see the Edit button on meeting requests that I initiated from Outlook on my PC so I wonder why it isn't available on others invitations to me?

I want to Edit those at times. For example, they may not include the address in the location field so I want to go in and edit the Event so I can put that information in to use later (look up directions in the Map App.

I'm new to iOS all together (my first iOS device is this iPhone 5) so not sure if this was available prior to iOS 6 or has always been an iOS calendar issue.

BTW I've upgraded to 6.0.1.

Thanks