Default Export Value

A default export value is the value used when a cell or cell region (e.g., a multi-column span or subtable block) is blank.

It is specified alongside Type or Subtable Type using the dataType=value syntax:

Type Definition	Default Export Value
int8=-1	-1
string=""	Empty string ""
duration=1ms	Duration of 1ms
enum@Rarity=common	Enum item common
>>[]int=/	Zero value (which evaluates to null)
vector|2|int8={}	Zero-valued vector [0, 0]
**map={}{}	Empty subtable map

If no default export value is specified, blank cells and cell regions result in an export error.

Note

Tree-structured data nodes may also have a default export value. If not specified, whether a missing node triggers an error is controlled by the presence option; an error occurs only when presence is set to required explicitly.

Shorthands

The following shorthands have fixed meanings:

Shorthand	Meaning
/	The type’s zero value (0 for integers, "" for strings, false for bool, null for []T, etc.). Example: int=/.
{}	An empty container or a zero-valued object. Example: []int={}, >>tuple|string|int={}.
{}{}	An empty container; additionally treats a blank (value) row as a zero-valued object. Only valid for fixed-size subtable arrays (**[N]) and subtable maps (**map). Example: **map={}{}.

Note

The quoted string "/" is the string literal /, not the zero-value shorthand.

Zero Value List

The / shorthand represents the following zero value for each type:

Type Category	Type(s)	Zero Value
Basic Types	int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64	0
	float, float32, float64	0
	string	""
	bool	false
	datetime	null
	duration	0s
	ref	0 or ""
	enum	0
	l10n	""
	path	""
	rgba	""
Passive Types	backref	0 or ""
	backref-n	null
	origin	auto-determined
Compact Types	>>[]T	null
	>>[N]T	null
	>>map[K]V	null
	>>object	null
	>>minmax	{min/max: zero}
	>>wtpool	null
	>>tuple	null
	>>vector	{x/y/z/w: zero}
Multi-Column Types	[]T	null
	[N]T	null
	map[K]V	null
	minmax	{min/max: zero}
	wtpool	null
	tuple	null
	vector	{x/y/z/w: zero}
	bitflags	0
Subtable Types	**[]	null
	**[N]	null
	**map	null
Behavior Types	anchor	""
	assert	true
	condition	true
	switch	""
	placeholder	—
Non-Leaf Types	[]	null
	[N]	null
	map	null
	{}	null
	minmax	{min/max: zero}
	wtpool	null
	vector	{x/y/z/w: zero}

Note: The zero values of certain data types may differ slightly in representation from what is listed in the table, but their semantics remain unaffected. For example, duration is listed as 0s, but actually appears as null.