This field allows to display if the user of the item belongs to a group (will display Yes or No) or to display since when he is in the group

The parameter contains

• the name of the group
• eventually the string 'date'

Example:
Teachers
Teachers,date

To work the tracker must have a field of type user selector with option 1 (creator).

For instance, you can use that field in a tracker, and then request with a PluginTrackerList to list all records from a user tracker which belong to a specific group, and show all their details: phone, address, etc.

Steps to follow:
1. Create a Tracker: Start by creating a tracker and name it, for example, "In Group Teachers."
2. Add a User Field:

• Add a field to the tracker and name it "User."
• Set the field type to User Selector to allow selecting users.

3. Add a Group Field:

• Add another field to the tracker and name it "Group Name."
• Set the field type to In Group.
• Click Add Field & Edit Advanced Options.

4. Configure Group Options:

• Locate the section titled Options for In Group.
• In the Group Name input field, specify the name of the group you want to check for user membership, here Teachers.

This setup will let you track users and determine if they belong to a specific group.
Try in wiki page using PluginTrackerListlike :

! In Group Teachers?
{trackerlist trackerId=""} 

would produce(accordingly to your records):

Click to expand

See also: User Groups tracker field, which is more powerful.