The type of the name of the group fields
ReadonlydigitThe character set used for representing digits in the fractional index.
ReadonlygroupThe fields that define the grouping context for the fractional index. This is an array of field names.
ReadonlylengthThe character set used for encoding the length of the integer part.
Optional ReadonlytypeThe type of the fractional index.
Must be "string" or undefined for string fractional indices.
The options for the string fractional index fields.
Example
See