Secure coding practices

Hi,

I'm looking to create some examples of secure vs non-secure code in RPG.
I'm not finding it easy to come up with my own. I guess the most basic
would be not checking the indicator after a chain operation, for example.
But nobody does that(!) Then I thought of a few things that tend to bite
you on the backside after a few weeks like a DS not initialized or nested
DO's with file reads that both use %EOF without specifying the file name.
But that only happens when you don't test properly. Anyone got any ideas?
TIA!