For web/gap media, the printer senses the differences between the label and the liner to determine the print format length.
For continuous roll media, the printer only senses the media’s characteristics. The print format’s length is set by programming (driver or software) or the last stored form’s length.
For black mark media, the printer senses the beginning of the mark and the distance to the start of the next black mark to measure the print format length.
For other common media and setting variations: