A class consists of several subobjects, such as a public section, method implementation, or local class includes. Each subobject can be assigned separately to a transport request.
If you want to edit an ABAP class where the changes have already been assigned to a transport request by another user, you can assign your changes to a different transport request.
The source code editor will then use and assign all of your changes to the selected transport request.
Your changes are stored, assigned to the selected transport request, and can now be transported to subsequent systems through your releasing the transport request.
In the marker bar of the ABAP source code editor, you can display the following icons that highlight the subobjects of the ABAP class to which the changes are assigned
When you hoverover the icon, a popup is opened that displays the:
If you wish that ABAP Development Tools (ADT) displays the icon, you will need to activate the following setting in the Preferences page: