The generation of unique identifiers is worth some thinking because a shorthand will go a long way in keeping the code clean.
Starting with an example, if a data element is referenced as "D16057U2" this indicates access to deployment D16057 as user U2.
This example is taken from docs.s3db.org, targeting deployment at http://ibl.mdanderson.org/beta and entering without key.
D16057U2I44828" with all the information about the Item "Illumina 550K ...". This indicates not just the location but also the user (this is U2, the public user, not the entry creator, Lena) whose permission should be use to decide what contents are to be displayed.
If you are provided with "D16057U2I44828", how do you know which deployment to target?
Answer: you go to the register of all S3DB deployments, at root.s3db.org and look for project "root" where that information will be maintained.