Using the URL like that just shows the full "record" so no filter there but you could use this 

https://gwserver:9710/gwadmin-service/list/user.csv?attrs=domain,postoffice,name,visibility&filter=name%20eq%20%27userID%27

where %20 is a space and %27 is a single quote

The above will create a csv file with the columns as in the attrs and for the user equal to the name provided, without the filter= all users in the system will be in the csv file. Also you can filter on there things like PO etc

Using the URL as you mentioned in an application/script you could parse the json data and get the visibility from there, the data you can see simply using Curl like this from a Linux server command line

curl -k --user admin:novell -X GET -H "Content-Type: application/json" https://gwserver:9710/gwadmin-service/domains/DOM/postoffices/PO/users/userID

Hi Rob,

that was very helpful and exactly what I was looking for!

With my test data and used with curl this URL produced:
doms01,pols01,name,visibility ,,SpechtB-S01,SYSTEM

Thank you very much!
Best regards, Uwe.