Wow - that's a lot of letters! Believe it or not, they are all related to asset tracking. The first two are mandates/rules for identifying items and the last two are the organizations/governing bodies that are proposing and/or enforcing them. I just returned from the UDI conference last week in Orlando. UDI - which stands for Unique Device Identification - is a new rule being proposed by the FDA. Now this is not to be confused with UID (Unique Item Identification) a mandate set forth by the Department of Defense in 2004.
The objective of both mandates is actually very similar - much like their acronyms - create a unique number which is then used to identify a specific item or device and, in the case of UID, track the item throughout its lifecycle. Both mandates are aimed at improving asset visibility with UDI's focus initially more on the supply chain side.
Having been heavily involved with UID for several years now I found the UDI conference very interesting. It reminded me of the first UID forum I attended four years ago in San Diego when people were just learning about UID and how it would impact them. At that time the UID spec was already out; whereas the UDI spec will not be finalized until next spring so right now people aren't 100% sure what will be required of them. Right now it doesn't appear that there will be a required technology, unlike UID where a 2D bar code is the actual UII mark. Bar code - both linear and 2D were discussed at the conference as well as RFID.
Even though it has been out there for a number of years, UID is still in its early stages with new contracts now including the requirement, some existing contracts being amended to incorporate UID and legacy deadlines in place for various items in 2010 and 2015. It will be very interesting to monitor the growth of UDI and see what other similarities the two mandates have besides their name.