Using if HTTP::header value Content-Type contains "text"

[root@ve1023:Active] config  b virtual bar list
virtual bar {
   snat automap
   pool foo
   destination 172.28.65.152:http
   ip protocol tcp
   rules myrule
   profiles {
      http {}
      tcp {}
   }
}
[root@ve1023:Active] config  b rule myrule list
rule myrule {
   when HTTP_REQUEST {
        if {[HTTP::header value johnsname] equals "default"} {
                log local0. "it is default"
        } else {
                log local0. "it is not default"
        }
}
}

[root@ve1023:Active] config  curl -I http://172.28.65.152/ -H "johnsname: default"
HTTP/1.1 200 OK
Date: Thu, 10 Nov 2011 16:31:32 GMT
Server: Apache/2.2.3 (CentOS)
Last-Modified: Tue, 08 Nov 2011 12:54:37 GMT
ETag: "4183c9-30-ac7cfd40"
Accept-Ranges: bytes
Content-Length: 48
Connection: close
Content-Type: text/html; charset=UTF-8

[root@ve1023:Active] config  curl -I http://172.28.65.152/ -H "johnsname: test"
HTTP/1.1 200 OK
Date: Thu, 10 Nov 2011 16:31:39 GMT
Server: Apache/2.2.3 (CentOS)
Last-Modified: Tue, 08 Nov 2011 12:54:37 GMT
ETag: "4183c9-30-ac7cfd40"
Accept-Ranges: bytes
Content-Length: 48
Connection: close
Content-Type: text/html; charset=UTF-8

[root@ve1023:Active] config  tail /var/log/ltm
Nov 10 08:31:18 local/tmm info tmm[4766]: Rule myrule : it is default
Nov 10 08:31:24 local/tmm info tmm[4766]: Rule myrule : it is not default