Use UUID for local identifiers
Currently in Morpho 2.x development we are using a "scope.XX" format for our local identifiers. The "XX" is incremented whenever the need arises for a new identifier, whether as a revision to the previous package or as a new data file or as a new data package. This can be confusing because you might infer relationships between packages as older or newer even though they have no relationship to one another.
If we went with UUID locally we would have very opaque/very unique identifiers and would not be at risk of tricking people with faulty semantics. The downside is that they are long and not user friendly.
When it came time to save them to the network the likelihood of collision is als very low.
When it came time to "publish them" (see bug #5799) we would have the EZID service generate a [shorter] DOI for us so that it would be more friendly for print media and citations.