# Trigger Processing

User definable "trigger" processing can be written to occur when the designated event happens. In filePro, these types of processing are given labels and that is where the processing starts up when the trigger is pulled. This is called "when processing" and spoken aloud as "when enter selection", "when entering field nnn", "when leaving field nnn", and sometimes "@when leaving field n" or "@key X", etc. The @ starting all these labels may be considered to mean "at", or "at the moment when this trigger is activated".