SpecDefinition referenceView source

Date Variable

A calendar date as an ISO YYYY-MM-DD string. No time zone and no clock are involved. '{{<id>}}' inserts it formatted with 'format'.

Metadata

Definition: #/$defs/DateVariable
Form: object
Source: spec/schemas/opf.schema.json

Field index

Field	Type	Req.	Description
type	const	yes	Variable kind. One of color, text, number, date, image, url or list. `type` · Allowed values `"date"`
value	string	—	ISO calendar date (YYYY-MM-DD) this variable resolves to.
required	boolean	—	Whether the variable must be filled. Defaults to true: a variable with no 'value' is unfilled, and an unfilled required variable is an error in a normal deck and expected in a template. Set false for an optional slot: an unfilled optional variable resolves to empty text (inline tokens) or the field that references it is omitted.
label	string	—	Optional short human label for forms and fill panels.
description	string	—	Optional prose describing what the variable is for, surfaced by pickers, fill forms and agents.
example	string	—	Illustrative ISO date shown in fill forms and used when a template is previewed with examples. Never written to output.
format	string	—	Date display pattern, the same LDML-style tokens as header/footer dateFormat: yyyy, yy, MMMM, MMM, MM, M, dd, d, EEEE, EEE and quoted literals. English names. Default 'MMMM d, yyyy'.

`type`

typeconstrequiredyesdefault—

Variable kind. One of color, text, number, date, image, url or list.

type · Allowed values: "date"

Field fragment · type.json

{
  "type": "date"
}

`value`

typestringrequirednodefault—pattern^\d{4}-\d{2}-\d{2}$

ISO calendar date (YYYY-MM-DD) this variable resolves to.

`required`

typebooleanrequirednodefaulttrue

Whether the variable must be filled. Defaults to true: a variable with no 'value' is unfilled, and an unfilled required variable is an error in a normal deck and expected in a template. Set false for an optional slot: an unfilled optional variable resolves to empty text (inline tokens) or the field that references it is omitted.

`label`

typestringrequirednodefault—

Optional short human label for forms and fill panels.

`description`

typestringrequirednodefault—

Optional prose describing what the variable is for, surfaced by pickers, fill forms and agents.

`example`

typestringrequirednodefault—pattern^\d{4}-\d{2}-\d{2}$

Illustrative ISO date shown in fill forms and used when a template is previewed with examples. Never written to output.

`format`

typestringrequirednodefault—

Date display pattern, the same LDML-style tokens as header/footer dateFormat: yyyy, yy, MMMM, MMM, MM, M, dd, d, EEEE, EEE and quoted literals. English names. Default 'MMMM d, yyyy'.

Field fragment · format.json

{
  "format": "MMMM d, yyyy"
}

Complete definition constraints

Exact schema constraints

{
  "type": "object",
  "required": [
    "type"
  ],
  "additionalProperties": false,
  "properties": {
    "type": {
      "type": "string",
      "const": "date",
      "description": "Variable kind. One of color, text, number, date, image, url or list."
    },
    "value": {
      "type": "string",
      "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
      "description": "ISO calendar date (YYYY-MM-DD) this variable resolves to."
    },
    "required": {
      "type": "boolean",
      "default": true,
      "description": "Whether the variable must be filled. Defaults to true: a variable with no 'value' is unfilled, and an unfilled required variable is an error in a normal deck and expected in a template. Set false for an optional slot: an unfilled optional variable resolves to empty text (inline tokens) or the field that references it is omitted."
    },
    "label": {
      "type": "string",
      "description": "Optional short human label for forms and fill panels."
    },
    "description": {
      "type": "string",
      "description": "Optional prose describing what the variable is for, surfaced by pickers, fill forms and agents."
    },
    "example": {
      "type": "string",
      "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
      "description": "Illustrative ISO date shown in fill forms and used when a template is previewed with examples. Never written to output."
    },
    "format": {
      "type": "string",
      "description": "Date display pattern, the same LDML-style tokens as header/footer dateFormat: yyyy, yy, MMMM, MMM, MM, M, dd, d, EEEE, EEE and quoted literals. English names. Default 'MMMM d, yyyy'.",
      "examples": [
        "MMMM d, yyyy",
        "dd MMM yyyy",
        "M/d/yyyy",
        "EEEE, MMMM d"
      ]
    }
  },
  "description": "A calendar date as an ISO YYYY-MM-DD string. No time zone and no clock are involved. '{{<id>}}' inserts it formatted with 'format'."
}