<listitem>
<para>
Allows you to specify an arbitrary PQF query language substring.
- The provided string is prefixed the user's query after it has been
+ The provided string is prefixed to the user's query after it has been
normalized to PQF internally in pazpar2.
This allows you to attach complex 'filters' to queries for a given
target, sometimes necessary to select sub-catalogs
<literal>@and @attr 1=30 @attr 2=3 %Y %%</literal>
would search for current year combined with the original PQF (%%).
</para>
+ <para>
+ This setting can also be used as more general alternative to
+ pz:pqf_prefix -- a way of embedding the submitted query
+ anywhere in the string rather than appending it to prefix. For
+ example, if it is desired to omit all records satisfying the
+ query <literal>@attr 1=pica.bib 0007</literal> then this
+ subquery can be combined with the submitted query as the second
+ argument of <literal>@andnot</literal> by using the
+ pz:pqf_strftime value <literal>@not %% @attr 1=pica.bib
+ 0007</literal>.
+ </para>
</listitem>
</varlistentry>