$Y contains an integer value ranging from 0 to 65,535 specifying the vertical position of a virtual cursor in the current output page. $Y=0 represents the top row or line.

Every OPEN device has a $Y. However, M only accesses $Y of the current device. Therefore, exercise care in sequencing USE commands and references to $Y.

When GT.M finishes the logical record in progress, it generally increments $Y. GT.M recognizes the end of a logical record when it processes certain M format control characters, or when the record reaches its maximum size, as determined by the device WIDTH, and the device is set to WRAP. The definition of "logical record" varies from device to device. For an exact definition, see the sections on each device type. Write filtering and the device LENGTH also have an effect on $Y.

$Y never equals or exceeds the value of the device LENGTH. Whenever it reaches the value equal to the device LENGTH, it gets reset to zero (0)

GT.M permits an M routine to SET $Y. However, SET $Y does not automatically issue device commands or escape sequences to reposition the physical cursor.

For more information on $Y, refer "Input/Output Processing".