TES3

Main Header Record, 308 bytes

TES3 record sub-records detail:

HEDR (300 bytes)
    4 bytes, float Version (1.2)
    4 bytes, long Unknown (1)
    32 Bytes, Company Name string
    256 Bytes, ESM file description?
    4 bytes, long NumRecords (48227)
MAST = string, variable length
    Only found in ESP plugins and specifies a master file that the
    plugin requires.  Can occur multiple times.  Usually found just
    after the TES3 record.
DATA = 8 Bytes  long64 MasterSize
    Size of the previous master file in bytes (used for version
    tracking of plugin). The MAST and DATA records are always found
    together, the DATA following the MAST record that it refers to.