BX is a file format for alphabets used by Embrilliance embroidery software. There is a free version you can download that you can install BX fonts in and then you are able to "type" in the lettering you need instead of bringing in one letter at a time to build your lettering like you need to do with other purchased sewing format files. There are also versions of Embrilliance that you can purchase to build yourself an embroidery suite with the functions you need to digitize, etc. Here is a link to their website:
https://embrilliance.com/
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