+The current query language is a bit awkward, but functional:
+
+query ::= complex | simple | attr query.
+complex ::= operator query query.
+operator ::= '@and' | '@or' | '@not'.
+simple ::= term | set.
+term ::= <word> | '"' <term> ... '"'.
+set ::= '@set' <setname>.
+attr ::= '@attr' <number> '=' <number>.
+
+Eg.:
+
+Andersen
+
+"Hans Andersen"
+
+@and @attr 1=1 andersen @attr 1=4 @attr 4=2 duckling
+