Possible compatibility problems with earlier versions marked with '*'.
+Proximity operator added to Prefix Query Format (PQF).
+
In test client command "base" accepts multiple databases.
Fixed bug in cs_close stack that caused trouble with WINSOCK.
The current query language is a bit awkward, but functional:
-query ::= ['@attrset' <attribute-set>] rpn
-rpn ::= complex | simple | attr rpn
-complex ::= operator rpn rpn
-operator ::= '@and' | '@or' | '@not'.
-simple ::= term | set.
-term ::= <word> | '"' <term> ... '"'.
-set ::= '@set' <setname>.
-attr ::= '@attr' [<attribute-set>] <number> '=' <number>.
+query ::= ['@attrset' <attribute-set>] rpn
+rpn ::= complex | simple | attr rpn
+complex ::= operator rpn rpn
+operator ::= '@and' | '@or' | '@not' | '@prox' proximity
+simple ::= term | set.
+term ::= <word> | '"' <term> ... '"'.
+set ::= '@set' <setname>.
+attr ::= '@attr' [<attribute-set>] <number> '=' <number>.
+proximity ::= exclusion distance ordered relation which unit
+exclusion ::= '1' | '0' | 'void'
+distance ::= <number>
+ordered ::= '1' | '0'
+relation ::= <number>
+which ::= 'known' | 'private'
+unit ::= <number>
Eg.: