Esx

This article is not complete yet, work in progress

Format of Morrowind's ESM Plug-In File

Basic Overall Format:

The ESM/ESP/ESS files are composed entirely of Records with this format.

Record

4 bytes: char Name[4]
    4-byte record name string (not null-terminated)
4 bytes: long Size
    Size of the record not including the 16 bytes of header data.
4 bytes: long Header1
    Unknown value, usually 0 (deleted/ignored flag?).
4 bytes: long Flags
    Record flags.
         0x00002000 = Blocked
         0x00000400 = Persistant
? bytes: SubRecords[]
    All records are composed of a variable number of sub-records. There
    is no sub-record count, just use the record Size value to determine
    when to stop reading a record.

Sub-Record

The sub-record is the tail of the record and it contains data specific to the record type.

4 bytes: char Name[4]
    4-byte sub-record name string (not null-terminated)
4 bytes: long Size
    Size of the sub-record not including the 8 bytes of header data.
? bytes: Sub-Record data.
    Format depends on the sub-record type.

Record types

Tes3, Main header record.

Gmst, Game setting record.