quantity type "string" failing in yaml schema

Seting a quantity type string fails in a yaml schema, but str works fine. However, the docs say that string should be possible. https://nomad-lab.eu/prod/v1/staging/docs/archive.html

In the example page https://nomad-lab.eu/prod/v1/staging/gui/dev/editquantity there is a suggestion for string that does not seem to work for an external user.