OpenSearch/rest-api-spec/api/search_template.json

{
  "search_template": {
    "documentation": "http://www.elasticsearch.org/guide/en/elasticsearch/reference/master/search-search.html",
    "methods": ["GET", "POST"],
    "url": {
      "path": "/_search/template",
      "paths": ["/_search/template", "/{index}/_search/template", "/{index}/{type}/_search/template"],
      "parts": {
        "index": {
         "type" : "list",
         "description" : "A comma-separated list of index names to search; use `_all` or empty string to perform the operation on all indices"
        },
        "type": {
          "type" : "list",
          "description" : "A comma-separated list of document types to search; leave empty to perform the operation on all types"
        }
      }
    },
    "body": {
      "description": "The search definition template and its params"
    }
  }
}