====/igg/invitationoptions====
Instead of assigning a co-player, users can also book a teetime with 1 or more open spaces. In these spaces they can invite other people to play with them. These can either be a self-defined special friends list (internally called a circle) or be a subselection of all golfers in the system (for instance all females with handicap 0-36).

Since it is no use inviting people on a very short term, this option should only be allowed to use for bookings at least 3 days in advance.

parameters:
|auth	|the authorisation code you received from Intogolf BV (mandatory)|
|relnr	|client id of the user that is making the booking |
|relkey	|the hash key that was provided upon login (mandatory if relnr>0)|

example: https://backend.ikgagolfen.nl/igg/invitationoptions?auth=<your authorisation code>&relnr=227529

result:
<code>{
  "invitationoptions": [
    {
      "cirnr": 283,
      "cirname": "weekendclub"
    },
    {
      "cirnr": 1,
      "cirname": "mijn vriendenlijst"
    },
    {
      "cirnr": 2,
      "cirname": "iedereen"
    },
    {
      "cirnr": 3,
      "cirname": "iedereen met hcp 36+"
    },
    {
      "cirnr": 4,
      "cirname": "iedereen met hcp 0-36"
    },
    {
      "cirnr": 5,
      "cirname": "dames"
    },
    {
      "cirnr": 6,
      "cirname": "dames met hcp 36+"
    },
    {
      "cirnr": 7,
      "cirname": "dames met hcp 0-36"
    },
    {
      "cirnr": 8,
      "cirname": "heren"
    },
    {
      "cirnr": 9,
      "cirname": "heren met hcp 36+"
    },
    {
      "cirnr": 10,
      "cirname": "heren met hcp 0-36"
    }
  ]
}</code>

if a wrong authorisation code is provided, the backend will return “no authorisation”