These tags look like 296x152 but the firmware only takes 152x296, so landscape BMPs get transposed. Tested on a real 2.6 color tag.
Co-authored-by: Cursor <cursoragent@cursor.com>
Pricer barcodes validate with (sum of all 17 chars) mod 10 == 0,
with the letter prefix contributing by its ASCII offset from '0'.
The old formula compared sum of the first 16 digits to the 17th,
rejecting valid codes like A4120365539013704.
