Var-Files.md

Every var file has two parts: a header and a number of entries, where an entry contains the data for a single variable. Usually, var files contain just one entry; in these cases, there's not much distinction between a var and an entry for the purposes of messing with its data.

TIHeader

Section	Subsection	Section Offset	Length	Type	Description	Notes
Header	Magic	0	8	String	The file magic for the var	Used to identify if the file is intended for the TI-82 (**TI82**), TI-83 (**TI83**), or TI-83+ and onward (**TI83F*)
	Extra	8	2	Bytes	Extra export bytes for the var	Exact meaning and interpretation of these bytes is not yet determined
	Product ID	10	1	Bytes	The product ID for the var	Used to identify the model the var was created on, though has no actual functional ramifications Does not constitute a 1-to-1 mapping to distinct models
	Comment	11	42	String	The comment attached to the var

TIEntry

Section	Subsection	Section Offset	Length	Type	Description	Notes
Meta Length	Meta Length	0	2	Integer	The length of the meta section of the entry	Indicates if the entry is suitable for a flash chip (13) or not (11) If equal to 13, the entry contains the starred meta subsections If equal to 11, the entry lacks the starred meta subsections
Meta	Data Length	0	2	Integer	The length of the data section of the entry
	Type ID	2	1	Bytes	The type ID of the entry	Used the interpret the contents of the data section of the entry
	Name	3	8	Varies	The name of the entry	Interpretation as text depends on the entry type; see entry pages for details
	Version*	11	1	Integer	The version number of the entry	Only known use is for programs and other tokenized types
	Archived*	12	1	Boolean	Whether the entry is archived
Data Length	Data Length	0	2	Integer	The length of the data section of the entry	Repeat of the value found in the meta section
Data	...	...	...	...	The data section of the entry	See entry pages for subsections

TIVar

Section	Subsection	Section Offset	Length	Type	Description	Notes
Header	Header	0	53	TIHeader	The var's header
	Entry Length	53	2	Integer	The total length of all entries in the var	Should be 57 less than the total var size
Entries	Entry 1	0	...	TIEntry	The first entry in the var
	...	...	...	TIEntry	Subsequent entries in the var	Most vars contain only one entry
Checksum	Checksum	0	2	Bytes	The checksum for the var	Equal to the lower 2 bytes of the sum of all bytes in the entries