sell-by date

[hela]

Dear teachers,
Would you please tell me how to analyse these phrases?

a) a sell-by date
b) the / a (?) best-by date
c) the / an expiry date

Are "sell-by / best-by / expiry" kind of adjectives?
Many thanks,
Hela

[Mister Micawber]

.
They must be, as they modify the noun date. I don't particularly like this construction (a & b), Hela, but it is certainly common in commercial English. (Expiry is simply a noun used adjectivally, of course.)

I presume you can figure out the expanded ellipsis: e.g. 'the date [which we must] sell [the product] by'.
.

[hela]

Thank you very much for your explanation, Mr Micawber