This gives the ability to do a low level format of a pre-existing NVMe Namespace. The Format NVM command allows setting the block size of the Namespace (e.g. 512B or 4KB), specifying the type of T10 Protection Information to use, or erasing the contents. Note that similar options exist when creating a Namespace via the Namespace Management command.
The command options allow directly specifying all 5 parameters given in the NVMe 1.3 spec.