Look up Shell in the help
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Shell(pathname[,windowstyle])
The Shell function syntax has these named arguments:
Part Description
pathname Required; Variant (String). Name of the program to execute and any required arguments or command-line switches; may include directory or folder and drive.
windowstyle Optional. Variant (Integer) corresponding to the style of the window in which the program is to be run. If windowstyle is omitted, the program is started minimized with focus.