Could someone kindly point me to where AUTHORIZENET_DEVELOPER_MODE is getting set?

My CC processesor is using the authorizenet_aim.php file as their base, but I don't seem to be getting into developer mode to debug...

I see a lot of defined(AUTHORIZENET_DEVELOPER_MODE );

but I don't see define(AUTHORIZENET_DEVELOPER_MODE , 'on'); anywhere

HELP!

Thanks

Matt