ripple/ripple-rest

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Currency",
  "description": "The three-character code or hex string used to denote currencies",
  "type": "string",
  "pattern": "^([a-zA-Z0-9]{3}|[A-Fa-f0-9]{40})$"
}