The author needs to use a workaround employing the Empty Where Clause Handling parameter to get a list of valid values in the browser. She then needs to type (or copy-paste) the value.

The definition of the documents for each value and the homepage for these values is a lot of work at first. But additional values are added quite simply.

The advantage is that these pages provide an additional navigation structure that makes it easy to find documents related to a value.