The following schema describes the JSON data structure used to indicate an action by ISPF:

{
  "ACTION":{
    "description":"The signal of an action by ISPF - EXIT=one or more ISPF logical
    screens has been exited",
    "type":"string",
    "enum":["EXIT"],
    "required":true
  },
  "SCR":{
    "description":"For an EXIT action request, a list of identifiers for each ISPF
    logical screen that has been exited",
    "type":"array",
    "items":{
      "description":"The identifier for the ISPF logical screen that has been exited",
      "type":"string",
      "maxLength":1
    }
  }
}