It would be nice if there was a "Require Unique Revision Numbers" checkbox in the "Sheet Issues/Revisions" dialog, OR change the Error into a Warning for "Revision Number "#" is used more than once." (similar to how we can have duplicate Type Marks).
We have a hotel renovation that's being done in multiple phases (in 10+ separate sets and permitted separately). This has resulted in us having multiple "1", "A", and "B" revisions for the various sets and submittals, see below. I've just had to explain the workaround yet again, and the alternate workaround of using "Issued to" or "Issued by" is also confusing, requires that the field isn't being used, and requires multiple tag families (though it's a little more obvious). Either workaround isn't that hard, but they're non-standard (and so require extra training).
