The parser is unable to handle masters with port declarations in a slave
zone specification.

This example won't be parsed correctly:
---
zone "example.com" {
                      type slave;
                      file "sec/example.com";
                      masters port 52 {
                                1.2.3.4;
                                2.3.4.5;
                        };
        };
---
leads to

parse error: Expected Fwuh?  `', saw 'port' following `masters' at
<filename>:4 at /usr/share/perl5/BIND/Conf_Parser.pm line 23


This one is parsed correctly:

zone "example.com" {
                      type slave;
                      file "sec/example.com";
                      masters {
                                1.2.3.4;
                                2.3.4.5;
                        };
        };


Happy hacking...

Alex
---
ii  libbind-confpa 0.95-3         Parser class for BIND configuration files