When printing labels, these can be requested to the carrier in different formats, if the carrier supports them.

There could be several reasons for doing so, from compatibility, performance, and more.


The label type can be selected at any carrier setup, in the General tab:



This list details the currently supported label types, and a brief explanation of them:


  • ZPL: Most common option, requests the label in ZPL code language; lightweight and efficient, but requires a ZPL compatible/compliant printer that can receive the code, and transform it to the graphical representation of the label to print it. 

  • PDF: Alternative to ZPL, requests the label in PDF format; affects performance, since conversion happens as part of the process, and the data to be transmitted averages from 50 to 100 times more than with ZPL, yet compatibility is greatly improved for printers that don't support ZPL

  • AZPL: Supported by the Stamps.com plugin only, works like ZPL, but instead of using the ^GFX command that downloads the graphic image code in binary format, it uses ^GFA which works in ASCII hexadecimal format
     
  • BZPL: Supported by the Stamps.com plugin only, works like ZPL, downloading the graphic image code in binary format

  • EPL: Supported by the Stamps.com plugin only, uses the EPL (Eltron) code language, older but simpler than ZPL, and required to be used if the printers you'll output the labels through need to use it

  • DPL: Supported by the Nationex plugin only, uses the DPL (Datamax) code language, and might be required to be used if the printers you'll output the labels through need to use it 

  • PNG: Alternative to ZPL or PDF whenever supported, requests the label in PNG format; affects performance, since the data to be transmitted is significantly higher than with ZPL, yet compatibility is greatly improved for printers that don't support ZPL, or that support it but might need to use it