What is the use of Standing Appointment?

Summary:

We would like to know what is the Standing appoitnment supposed to do, what is it use?

Content (please ensure you mask any confidential information):

In the Dock scheduling gantt legend, we have seen the Standing Appointment, which is supposed to be orange. We would like to know for what kind of shipments or situation could we use this flag

Version (include the version you are using, if applicable):

23C

Code Snippet (add any code snippets that support your topic, if applicable):