ABAP: sy-subrc

[Saint]

I see code like this all over my ABAP:

IF sy-subrc <> 0.

and I figure it is some error checking because it has below it

*   error handling

What are the other codes? Is this an error handling method?
I'm assuming *'s mean comment but you can't use them in the middle of a line like

do code ... * my code

[Jordan]

Yes, this is an error handling code. If it is 0 you have no errors. Double click on it for more info.

* are comments, only from the start of the line.

[smith]

sy-subrc is a system field which is the return code. ABAP programs will set this to 0 if execution is successfull or != (<>, not equal) 0 if otherwise.