Why is attribute ApprovalState nor configurable for REST API?

Hi all, 

we're using Standard REST API to request identity data. For this we created a system user and a group. Group gots priviledges on tabel person for reading data.
We're wondering why we can't configure group permissions on the attribute ApprovalState top allow view priviledges. 

In rest-api-reference-guide for method get single identity a example is shown which returns the attribute ApprovalState.
"uri": "https://<Hostname>/AppServer/api/entity/Person/83b10e84-c64e-4f9f-9ecb-2d0d7c94e8ec",
"display": "Bodewell, Jeremia (JEREMIAB)",
"values": {
"ApprovalState": 0,.


Our own test gives it back in another way without ApprovalState within values but with a "state"-attribute before the values:
"uri": "/api/entity/Person/08709512-77ba-4111-9112-ec6a4ebee61d",
"display": "Badstuber, Johnny (BADSTUBERJ)",
"state": 1,
"values": {
"BirthDate": "

1st question: Has the state attribute has something to to with the ApprovalState attribute and if yes, what does "state": 1 means?

2nd question: Why is attribute ApprovalState not returned in this API call and why we cannot set the priviledges on it? 

Thanks for any help. 
Best regards

Ulrich Kneisel