Hi,
What is the standard business object for ticket's assignment ?

In this Question i read that the standard BO is "activity", but in Repository Explorer (SDK) the definition doesn't says about it. So, is there any other object for ticket's assignment ?
In my scenario i have ticket and ticket's assignment without create task in activities.
Defintion:
Business Context and Use The Activity object is used to provide the necessary information to gain a structured overview of the business objects -Appointment Activity -E-Mail Activity -Phone Call Activity -Activity Task