tinydns syntax for virtual subhosting

I am new to tinydns and would like to verify that I understand the syntax for the data file. I am virtual hosting domains on the same IP. Is the following syntax correct?

############################
.maindomain.com::ns1.maindomain.com
@maindomain.com::mail.maindoman.com
=mail.maindomain.com:1.2.3.1
=ns1.maindomain.com:1.2.3.2
=www.maindomain.com:1.2.3.3
+ftp.maindomain.com:1.2.3.3
### subhost 1
.subdomain1.com::ns1.maindomain.com
@subdomain1.com::mail.subdomain1.com
+mail.subdomain1.com:1.2.3.1
+URL
### subhost 2
.subdomain2.com::ns1.maindomain.com
@subdomain2.com::mail.subdomain2.com
+mail.subdomain2.com:1.2.3.1
+URL
##############################

Thanks in advance for any advice

You might want to consider adding a start of authority / SOA record for the domains:

Zmaindomain.com:ns1.maindomain.com:hostmaster.maindomain.com

etc

other than that it looks ok - at the end of the day if it works, it works - if it doesn't then you're probably a lot better off posting your actual tinydns data file rather than obfuscating the domain names.