Here are the data structures with brief descriptions:

Cgcf_cd_status	CD status packet.The Continuous Data standard (from the CTBTO) requires some additional real-time status updates. These updates are sent in a CD status packet, which is decoded into a struct gcf_cd_status
Cgcf_data_hdr	Header details for a data block
Cgcf_generic_hdr	Generic header details shared by all GCF blocks
Cgcf_status_hdr	Header details for a status block
Cgcf_union_hdr	Header union type for parsing