Note Assistant tool (Transaction:SNOTE) can be used to implement SAP notes. During note implementation using SNOTE, if you have previously modified the source codings which SNOTE is supposed to change, the object is flagged with a yellow icon with message SCWN349 "corrections incompletley copied; see change display" as below:
In such cases, you can use Split-Screen Editor to adjust the corrections to your modifications.
Let me explain how to use Split-Screen Editor with an exmple as below:
Yellow traffic light occured on object FUNC RFC_MODIFY_R3_DESTINATION during note 1511584 implementation: 
The reason is that there is an German character that cannot be recognized by SNOTE:
ö is the german character which could not be recognized !!
(Such problems often happen when implementing sap notes in Non-Unicode systems. You can refer to note 1549103 for details.)
Because SNOTE cannot implement the corrections automatically, we have to do manual adjustment using split-screen editor.
Click the yellow traffic light for object RFC_MODIFY_R3_DESTINATION to enter splic-screen editor as below: 
Find the contact block: 
Delete the <Delete Block>:
The status after deleting the two codings of <delete block>: 
Insert the <Insert Block> as below: 
The status after inserting <Insert Block>: 
Click the "Copy" button to confirm the above manual changes: 
After clicking "Copy" button, back to the initial screen automatically. You must make sure the selection box is flagged: 
Continue
Click "Yes" button ton confirm and continue
Note 1511584 was completely implemented.