Only user have permission Edit can input choose the valuesvalue.
On In the issue screen Issue Screen, Jira have two mode ( issue create, issue viewIssue Create, Issue View).
In issue create Issue Create mode, permission Edit is required. The user can chosen choose the values in the custom field.
...
In issue view Issue View mode, the user have permission view or edit will see the value of the custom field.
...
Click on this custom field to go Edit mode.
...
if If user don’t have permission:image don’t have permission.
...
if the custom field is not configure.
image don’t have configure.
Number Field Security Group Picker get the value from the chosen custom field on Issue. The application will process the value (encode to store it, decode to show it).