S-language
Steve Selvin · 1998
Abstract The second most important command after Splus is q(_). This command ends an S-session and returns the computer to its operating system. The parentheses are an S-language convention that identifies input arguments, as will be seen. If only the command q is executed (no parentheses), SPLUS displays at the terminal the computer code invoked by the command and does not execute the command. This feature is a property of all S-functions.