Letterboxd username: letters, digits and `_`, e.g. `davidehrlich`. Input is lowercased. Required, no default; at most 64 characters.

Letterboxd film slug: letters, digits and hyphens, e.g. `parasite-2019`. Input is lowercased. Required, no default; 1 to 200 characters.

Entry number from the review URL (`/{username}/film/{slug}/{entry}/`). Omit it for the viewing without a number; `rewatch` tells you whether it is a rewatch.