How long can API variant values be?

How long can variant values (also called ‘options’ by the API) be? There’s no documentation on the subject, Google searches just return results on the maximum number of variants, and the automated Shopify help is anything but.

One of the values that we’re about to introduce could end-up being very long in the future. I want to know if a variant value that suddenly ends-up being a thousand characters in the future may end-up being refused by the API.