I think they meant "reference number" like some sort of "remember this code if anything goes wrong or we won't refund you" to return a product or something lol.

I think this is a major issue with such things though. There's so much paper mail especially where it says "keep for your records" but it's like... between some fuzzy limbo of necessity and garbage.

...so it either gets scanned to PaperlessNGX or gets stuffed in a "I want this stupid paper off my desk and I'm not sure if I should keep it" box that I'll go through when it's full. Lol