Expert Advisor Programming by Andrew R. Young

Custom Indicators and Scripts
Just like expert advisors and indicators, scripts use the init(), deinit() and start() functions.
Remember that each function will only be run once – init() and start() when the script is started,
and deinit() when it is removed. You can have one script attached to a chart at a time.
MetaTrader comes with several sample scripts. All scripts are saved in the \experts\scripts
directory.
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