refs, defs, schemas

hello.json

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "Person",
  "type": "object",
  "properties": {
    "contact": {
      "anyOf": [
        { "$ref": "#/$defs/emailContact" },
        { "$ref": "#/$defs/phoneContact" }
      ]
    }
  },
  "required": ["contact"],
  "$defs": {
    "emailContact": {
      "type": "object",
      "properties": {
        "email": { "type": "string", "format": "email" }
      },
      "required": ["email"]
    },
    "phoneContact": {
      "type": "object",
      "properties": {
        "phone": { "type": "string", "pattern": "^[0-9]{10}$" }
      },
      "required": ["phone"]
    }
  }
}