Information about creating new PNGs for Font file (GTR)

[gitzila]

Hello,
I found your Python-script very useful to create new Font (ft12) for Amazfit GTS with lots of emojis in it. But I do not really understand the format of filename. The verbose Output of unpack gives some hints, but some parts I do not understand. For example the value of w+ (maybe the width of the image when drawing?) and the meaning of the Bytes directly before w+. I would like to put more PNGs into the font file (especially for flags) but it does not work...
Can You please share any information you have about the structure of the ft-File and the construction of the PNGs filenames before packing?

Thanks a lot

Frank