Rx: Simple, Extensible Schemata
//map
A //map is a mapping of names to values in which all values are matched against the same schema.
The values parameter provides a schema used to validate each value of the map.
/.meta/map, the schema for //map definitions:
{ "type": "//map", "required": { "type": { "type": "//str", "value": "//map" }, "values": "/.meta/schema" } }