you are only required to identify yourself IF you are detained for an investigation of the possibility that you have committed a crime, are committing a crime, or are conspiring to commit a crime. Police may not detain you for simply walking down the street minding your own business.
Identify does not mean handing over a DL either. You only have to provide a name and an address at a minimum. Now, if that can be reasonably deemed insufficient because your name is John Smith, then you can be detained at the police department until your identity can be verified.