Oblivion Mod:File Format Conventions

Listed here are conventions used in describing Oblivion mod and save file formats. Many of these conventions are standard c-type conventions, others (e.g., iref) are specific to this subject.

C (Count)

This is used for mod subrecords.

Count	Usage
?	Unknown
+	Required
-	Optional
*	Repeating Repeat count may be zero. If subrecords are repeated in a group (e.g., MAST and DATA in TES4), then the following subrecords are indented under the leading subrecord.

Names/Comments

Text	Usage
num	Count of something. E.g. number of records.
size	Size in bytes of some data object.
?Huh?	Question or speculation.
[indent]	Substructure.

Data Types

Type	Size	Description
byte	1	Byte, signed.
ubyte	1	Byte, unsigned. Also used for unknown and/or complex data structures.
char	1	Character, signed. Used for text.
short	2	Short integer, signed.
ushort	2	Short integer, unsigned.
long	4	Long integer, signed.
ulong	4	Long integer, unsigned. Also used to represent a set of binary flags.
float	4	Floating point number
formid	4	A ulong used to identify a data object. May refer to a data object from a mod or new object created in-game.
iref	4	A ulong. Use as an index into the FormIDs Array to get the formId.
int64	8	Long 64-bit integer, signed.
uint64	8	Long 64-bit integer, unsigned.
hash	8	A hash of a string. See BSA File Format: Hash Calculation.
systemtime	16	SYSTEMTIME structure.
type[num]	num*sizeof(type)	Array of num types.
bstring	1+??	A string prefixed with a byte length. NOT zero terminated. This and other string types use Windows-1252 encoding. However, not all fields allow the full range -- e.g., editor ids are limited to [a-zA-Z0-9].
bzstring	1+??	A string prefixed with a byte length and terminated with a zero (\x00).
zstring	??	Zero terminated string. Size is size of string text + 1 for string terminator.
string	??	String which is not terminated Size is the exact number of characters in the string.
struct	??	Collection of other data types. Used to group items that logically belong together. E.g., pc cell data. Size is sum of item sizes.
list[len]	??	List of items of variable length, and possibly different types. Size is sum of item sizes.