Non-UTF-8 file encoding
The regulation binds filings to UTF-8. AliExpress filed file 11 in ISO-8859-1, and Temu filed files 3, 8, 9 and 11 in it, inconsistently within an otherwise UTF-8 bundle.
We attempt UTF-8 first, then fall back to Latin-1 and Windows-1252, and record the encoding each file used. UTF-8 is one of the regulation's two binding format requirements.