$c->domain_name = 'your.domain.name';
default: the domain name under which the site is being accessed
This is most useful in situations where you have a proxy cache in front of the website, and so the domain name calculated is the one which the proxy cache uses to access DAViCal, and not the 'real' domain name which client software uses to access the site.
This could also be used in cases where you wanted to make your host available under a number of domain names, but canonicalise them all to a particular one, but that sort of thing should really be solved through the use of mod_rewrite or simple redirects.
It is recommended that you do not set this unless you need it to get around proxy caching issues.
Available from DAViCal version: 0.0.0 and later