Thank you. I will review that file and see if I can figure it out. My immediate concern would be portability. By using the default font, I believe the printer automatically scales it for 300 or 600 dpi and rotates it for portrait or landscape. From your description, it does not sound like your suggestion does the same.
I also have no idea what the advantage would be. The way I did it uses 78 bytes, whereas the way you suggest is 175 bytes. I'm just too new to PCL to know best practices and what to avoid, but I'm always happy to learn new things.
Although FIM A is a fixed barcode, there are five different FIM barcodes, A through E. A FIM is basically 9 bits. The 9 positions of the barcode are either space or bar. All bars are identical.
The four character (ADFT) font you are thinking of is for the Intelligent Mail barcode (formerly known as the 4-State Customer Barcode) that replaced POSTNET and PLANET. I completed the IMb part before starting on FIM. I did review the USPS font, but it does not conform to the IMb specification as closely as I would like and is fairly bloated. For example, the specification shows Ascenders and Descenders as the same size (in inches), while in the sample font they are not. The specification shows a T:AD:F ratio of 1:2:3. Their font uses 15

29|30):44. So I created a new IMb font. Their font is 526 bytes in PCL, mine is 203 bytes and conforms to the IMb specification more closely. This allows more room for error in the printing process. Their font uses up much of that margin itself.