espocrm-base/application/Espo/Resources/metadata/fields/file.json

{
   "params":[
      {
         "name":"required",
         "type":"bool",
         "default":false
      }
   ],
   "actualFields":[
      "id"
   ],
   "notActualFields":[
      "name"
   ],
   "fieldDefs":{
      "skip":true
   },
   "filter": false,
   "linkDefs": {
      "type": "belongsTo",
      "entity": "Attachment"
   }
}