The go command transfers program control to another Proc statement which starts with a statement label. The second form is an indirect transfer, according to the value of the label, as extracted from a parameter in the input buffer.
The in command prompts for input from the terminal and places it in the secondary input buffer. Contents of the secondary input buffer are destroyed and the buffer pointer is set to the beginning, prior to placing data in the buffer. Leading and trailing blanks are removed and embedded blanks are replaced with a single attribute mark.
The is command temporarily stops execution of the Proc until a response is provided from the keyboard. Input is placed into the secondary input buffer. Any existing data at that location is overwritten. If the pointer is already at the end of the buffer, the input is appended to the end. The colon is the default prompt character.
The it command inputs data from the tape label of the currently attached magnetic media directly into the primary input buffer. The input buffer is cleared before the label is copied into it. If there is no label, the input buffer is cleared anyway. Note that the tape device must be attached.
The p command processes the commands in the currently active output buffers. The primary output buffer is processed first, followed by the secondary output buffer. Both the primary and secondary output buffers are automatically reset after the p command, and the active buffer pointer is reset to point to the primary output buffer.
The st command selects and directs output either to the primary output buffer (turns off the stack) or to the secondary output buffer (turns on the stack). When the stack is off, all data picked up by the a command is put in the primary output buffer. When the stack is on, the data is put in the secondary output buffer.