The PLANET barcode is either 12 or 14 digits long. This limitation is contributing to its supersession by OneCodeSOLUTION (OCS).
Like POSTNET, PLANET barcodes encodes the data in half- and full-height bars. Also like POSTNET, the barcode always starts and ends with a full bar (often called a guard rail) and each individual digit is represented by a set of five bars using a two-out-of-five code. However, in POSTNET, the two bars are full bars; in PLANET, the two-of-five are the short bars. As with POSTNET, the check digit is calculated by summing the other characters and calculating the single digit which, when added to the sum, makes the total divisible by 10.