If you want to insert a Postnet barcode in a template, then you need to insert a barcode element, where you select this as the barcode type:

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(The headers are links to the common description).

1. Data
   The data, that you want to put into the barcode.
2. Preview placeholder
   Here you can enter a text constant for the data, that you want to use for the barcode in the result view in the designer.
3. Module width
   The width of the lines of the barcode. This is rounded to up to a whole number of dots in the selected output resolution (DPI). For the mime types, ZPL and Direct protocol the resolution/DPI is set on the printer and for PCL/PDF output the resolution is set on the template element in the template.
4. Display text
   Enable this to display the data of the barcode also a human readable text.
5. Checksum mode
   How to handle the optional checksum.
6. Text placement
   This has only effect, if the Display text option above is enabled. The possible values are:
   BOTTOM: Display the text below the barcode.
   TOP: Display the text above the barcode.
7. Error handling
   How InterformNG2 should react, if the data used cannot be converted into the barcode e.g. because of unsupported characters.