{
  "$schema":                  "https://json-schema.org/draft/2020-12/schema",
  "$id":                      "https://schemas.mpai.community/OSD/V1.5/data/TimeExpression.json",
  "title":                    "Time Expression V1.5", "type": "object", "required": ["Header", "Kind", "Trace"], "additionalProperties": false,
                              "properties": {

    "Header":                 { "type": "string", "pattern": "^OSD-TEX-V[0-9]{1,2}[.][0-9]{1,2}$" },

    "InstanceID":             { "type": "string", "description": "Identifier of TimeExpression instance (unique within its context)." },

    "TimeExpressionID":       { "type": "string", "description": "Globally unique identifier for this TimeExpression definition." },

    "Kind":                   { "type": "string", "description": "Expression type selector.", "enum": ["absolute","interval","relative","coded","schedule"] },

    "Absolute":               { "type": "object", "additionalProperties": false, "description": "Absolute Time.", "properties": {
      "Value":                { "$ref": "https://schemas.mpai.community/OSD/V1.5/data/Time.json", "description": "Time instant (Time.json)." },
      "Label":                { "type": "string", "description": "Human-friendly label for the absolute time." } } },

    "Interval":               { "type": "object", "additionalProperties": false, "description": "Time Interval.", "properties": {
      "Start":                { "$ref": "https://schemas.mpai.community/OSD/V1.5/data/Time.json", "description": "Start time (Time.json)." },
      "End":                  { "$ref": "https://schemas.mpai.community/OSD/V1.5/data/Time.json", "description": "End time (Time.json)." },
      "Closed":               { "type": "string", "description": "Endpoint inclusion semantics.", "enum": ["both","left","right","none"], "default": "both" },
      "Approximate":          { "type": "boolean", "description": "Boundary times may be approximate.", "default": false } } },

    "Relative":               { "type": "object", "additionalProperties": false, "description": "Relative Time.", "properties": {
      "Anchor":               { "$ref": "https://schemas.mpai.community/OSD/V1.5/data/Time.json", "description": "Anchor time (Time.json)." },
      "Quantity":             { "type": "number", "description": "Numeric offset magnitude." },
      "Unit":                 { "type": "string", "description": "Offset unit.", "enum": ["seconds","minutes","hours","days","weeks","months","quarters","years"] },
      "Approximate":          { "type": "boolean", "description": "Computed target may be approximate.", "default": false } } },

    "Coded":                  { "type": "object", "additionalProperties": false, "description": "Coded Time.", "properties": {
      "Pattern":              { "type": "string", "description": "Coded pattern selector.", "enum": ["season_year","weekday_next_week","weekday_this_week","named_period"] },
      "Season":               { "type": "string", "description": "Season (for season_year).", "enum": ["spring","summer","autumn","winter"] },
      "Year":                 { "type": "integer", "description": "Year (for season_year)." },
      "Weekday":              { "type": "string", "description": "Weekday code.", "enum": ["MO","TU","WE","TH","FR","SA","SU"] },
      "WeekOffset":           { "type": "integer", "description": "Integer offset for next/this week patterns." },
      "Anchor":               { "$ref": "https://schemas.mpai.community/OSD/V1.5/data/Time.json", "description": "Reference time used by certain coded computations." },
      "Named":                { "type": "string", "description": "Named period.", "enum": ["end_of_month","start_of_quarter","end_of_quarter","start_of_year","end_of_year"] },
      "Approximate":          { "type": "boolean", "description": "Result may be approximate.", "default": false } } },

    "Schedule":               { "type": "object", "additionalProperties": false, "description": "Time Schedule.", "properties": {

      "Dtstart":              { "$ref": "https://schemas.mpai.community/OSD/V1.5/data/Time.json", "description": "Start date/time of the schedule (Time.json)." },

      "RruleObject":          { "type": "object", "additionalProperties": false, "description": "RRULE Object (structured form).", "properties": {
        "Freq":               { "type": "string", "description": "Frequency.", "enum": ["DAILY","WEEKLY","MONTHLY","YEARLY"] },
        "Interval":           { "type": "integer", "description": "Interval between recurrences.", "minimum": 1, "default": 1 },
        "Count":              { "type": "integer", "description": "Number of occurrences.", "minimum": 1 },
        "Until":              { "$ref": "https://schemas.mpai.community/OSD/V1.5/data/Time.json", "description": "End date/time for recurrence (Time.json)." },
        "ByDay":              { "type": "array", "description": "Array of weekdays.", "items": { "type": "string", "enum": ["MO","TU","WE","TH","FR","SA","SU"] } },
        "ByMonth":            { "type": "array", "description": "Array of months.", "items": { "type": "integer", "minimum": 1, "maximum": 12 } },
        "ByMonthDay":         { "type": "array", "description": "Array of month days.", "items": { "type": "integer", "minimum": -31, "maximum": 31 } } } },

      "RruleString":          { "type": "string", "description": "RRULE string per RFC 5545." },

      "Rdate":                { "type": "array", "description": "Array of explicitly included dates (Time.json).", "items": { 
                                "$ref": "https://schemas.mpai.community/OSD/V1.5/data/Time.json" } },

      "Exdate":               { "type": "array", "description": "Array of explicitly excluded dates (Time.json).", "items": { 
                                "$ref": "https://schemas.mpai.community/OSD/V1.5/data/Time.json" } } } },

    "Rights":                 { "$ref": "#/$defs/Rights" },
    "DataExchangeMetadata":   { "$ref": "https://schemas.mpai.community/AIF/V3.0/data/DataExchangeMetadata.json" },
    "Trace":                  { "$ref": "https://schemas.mpai.community/AIF/V3.0/data/Trace.json" },
    "DescrMetadata":          { "type": "string", "maxLength": 2048 } },

  "allOf":                    [
    { "if": { "properties": { "Kind": { "const": "absolute" } } }, "then": { "required": ["Absolute"] } },
    { "if": { "properties": { "Kind": { "const": "interval" } } },  "then": { "required": ["Interval"] } },
    { "if": { "properties": { "Kind": { "const": "relative" } } },  "then": { "required": ["Relative"] } },
    { "if": { "properties": { "Kind": { "const": "coded" } } },     "then": { "required": ["Coded"] } },

    { "if": { "properties": { "Kind": { "const": "schedule" } } },
      "then": { "required": ["Schedule"], "properties": { "Schedule": { "required": ["Dtstart"] } } } } ],

"$defs": {

    "Rights":                 { "type": "array", "minItems": 1, "items": { "oneOf": [

      { "type": "object", "additionalProperties": false, "required": [ "Right" ], "properties":
        { "Right": { "$ref": "https://schemas.mpai.community/MMM4/V2.2/data/Right.json" } } },

      { "type": "object", "additionalProperties": false, "required": [ "RightID" ], "properties":
        { "RightID": { "type": "string" } } } ] } } } }