BlockHeader
This is a ROS message definition.
Source
# Blockheader including time header for all ROS messages that publish SBF blocks
uint8 sync_1
uint8 sync_2
uint16 crc
uint16 id
uint8 revision
uint16 length
uint32 tow # ms since week start
uint16 wnc # weeks since Jan 06, 1980 at 00:00:00 UTC