[sheetjs]

".docx is a bad example, because it was standardized"

This is not 100% correct. A large part of the format is standardized in ECMA-376 and ISO/IEC 29500, but many details are implementation-dependent. Many of those details are covered under other specifications like [MS-DOCX] that are covered by a covenant not to sue, but other details are not covered and are therefore in murky legal territory.

[MS-DOCX] https://docs.microsoft.com/en-us/openspecs/office_standards/...

[jchw]

Ah, just another reason this example was not very good. It’s a complicated one.