Prefix Handlers allow you to refine queries by targeting specific index fields or
change the behavior of the query expansion.
For example, the title: prefix handler allows you to refine the search on
document titles.
You use prefix handlers in UQL
by prefixing your query with a given prefix, followed by colon (:) or a
numerical comparison operator like >. For example, the 'title' prefix
handler allows you to narrow the search on document titles, by looking only for matches within
the 'title' index field.
Important:
There must be a default prefix handler in your configuration. In the
default configuration, this prefix handler is text. It is used as fallback
when no prefix handler is specified in your UQL queries.