There exists two documents AN11808 and AN11807 that is under Non Disclosure Agreement. They contain an example how to communicate with the ICODE DNA tag. I'm currently trying to find out if there are any documents describing the ICODE DNA specific Command Codes, Block addresses, register bit maps, etc
Other than that there are the following ISO documents that might be of interest for you.
ISO_IEC_15693-3_2009
ISO_IEC_15693-3_2009_Amd_4_2017
ISO_IEC_29167-10_2017