properties.schema

{
  "type":"object",
  "$schema": "http://json-schema.org/draft-04/schema",
  "id": "http://jsonschema.net",
  "properties":{
    "_supportedLayout": {
      "type": "string",
      "enum": ["full-width", "half-width", "both"],
      "default": "both",
      "editorOnly": true
    },
    "instruction": {
      "type": "string",
      "default": "",
      "inputType": "Text",
      "validators": [],
      "help": "This is the instruction text",
      "translatable": true
    },
    "_items": {
      "type": "array",
      "title": "Table cells",
      "items": {
        "type": "object",
        "properties":{
          "_header": {
            "type": "array",
            "default": "",
            "title": "Table header",
            "properties":{
              "text": {
                "type": "string",
                "default": "",
                "title": "Cell text",
                "inputType": "TextArea",
                "validators": [],
                "help": "",
                "translatable": true
              }
            }
          },
          "_cells": {
            "type": "array",
            "default": "",
            "title": "Table cell",
            "properties":{
              "text": {
                "type": "string",
                "default": "",
                "title": "Cell text",
                "inputType": "TextArea",
                "validators": [],
                "help": "",
                "translatable": true
              }
            }
          }
        }
      }
    }
  }
}