NDMP Environment variable DATA_BLOCK_SIZE no longer supported?

I don't see any referene to the NDMP environment variable "DATA_BLOCK_SIZE" in new Data OnTap docs (8.3 Tape Protection Guide ).  However, when I open an NDMP connection to an OnTap 8.3 filer I do see this value in the list of default NDMP environment variables in the NDMP_CONFIG_GET_BUTYPE_INFO response.  I was hoping that the NDMP server would return this back at the end of backups also.