Thanks for the reply (I note lots of non-explained downvotes, which are always frustrating in response to an earnest question). Debian reference was perhaps no

Thanks for the reply (I note lots of non-explained downvotes, which are always frustrating in response to an earnest question). Debian reference was perhaps not useful -- more a comparison for vintage of code in use. I appreciate that it's a grey area, and I grew up coding 6502 & 6510 assembly on C64, hence the interest in reading through the pdf's provided. It's more the 'non-commercial usage is okay' caveat for the release. I genuinely don't know if there's a possibility of commercial use, or, beyond that question, why the restriction would be placed (it seems extremely unlikely it's for financial reasons).