Documentation/AlgoCode/Function reference
sell
Open a short, or close a long when the script is long only or once.
sell
Inside a when body. long only turns sell into an exit. once (without short only) does the same — one trade at a time, so sell closes the long instead of reversing. short only uses sell as the entry.
Return value
signal -1
Example
short only when ema(9) crosses below ema(21) sell