There are various ways to start the Splitscreen Editor:
Transaction SE39
You can display, change, compare, and save two code extracts in the Splitscreen Editor. The extracts may be in the same system, or one of them may be in a remote system.
You cannot change or save program source code from a remote system and you cannot navigate inside the remote system.
From the Modification Assistant
The Splitscreen Editor has an editing window on the left, and a display window on the right. The old SAP source code, which was modified by the customer, appears in the display window. Modified lines of code are flagged in the editor. You cannot switch the right-hand window to change mode. The new SAP source code appears in the left window in editing mode. The source code cannot be edited directly. You can only use functions like Delete, Insert and Replace. The system compares the two versions and marks the differences on both sides. There is also a function that allows you to select a single block in the display window. You can then copy it to the corresponding position in the editing window. It is also possible to copy source code to the editing window using Select, Copy to buffer, and Insert.
From the Version Manager
You can use the Splitscreen Editor in the version management:
The two versions appear in list mode
The Splitscreen Editor is now the default tool for displaying versions.
If you compare an active or modified version with an other version, it is also possible to edit the active or modified version
From the ABAP Editor
If there is data on the clipboard during an ABAP Editor session, you can use the Splitscreen Editor to compare the two versions. The system starts the editor in compare mode. You can change the database version. You cannot change the version that was stored temporarily.