Let's say you have exit variable code that using TYPE RSR_S_RANGESID that works before upgrade to 740 SP2 above. Before upgrade, component LOW of RSR_S_RANGESID is defined as TYPE CHAR, now it is with TYPE SSTRING (Note 1823174). Therefore you will get a syntax error that complains offset action doesn't work with STRING or XSTRING.
It might be a bit confusing to find the exact solution in Note 1823174 to fix the syntax error for a green hand in latest ABAP. In such situation, SCI (Code Inspector) can help you to map the error you hit with the solution in the Note.
In transaction SE38 etc you can directly call SCI check as below:
At first run, you may get no syntax error found. This is because the default variant for SCI needs some adjustment.
You can create the DEFALT variant as below: (If already created, change it)
Make sure Syntax Check is ticked.
The you will get the syntax error message code "MESSAGE\9":
Now you can search "MESSAGE\9" inside Note 1823174 and get following remedy:
Follow this instruction, you could change the codes to overcome the data type change:
Here you might find the ABAP help about STRING function and experssions is very helpful. You could access ABAP help by click F1 in ABAP editor.