Querying format:cassette works fine to search for Cassette releases but it is more difficult to search for 3.5" Floppy Disk releases, because " must be escaped. Many other medium formats have unusual separators.
To ease such query, it should be possible to search for medium format using a slug instead, that is, not only case-insensitive but also tolerant to spaces and separators. The above example would become easier by querying format:3-5-floppy-disk.
Another benefit is that it allows to replace quotation mark with typographically-correct character in medium format names without breaking search queries.