What is a root name?

A root name is an identifier for a particular package. Software should have a root name for each of it's packages. A root name is made of four parts:

The domain name and package name are separated by a slash. The package name, software version number and package number are separated by a colon. The package number is optional, if it isn't present, a value of zero is assumed. The software version may be optional in some contexts. If it's missing, we say it's an "unversioned rootname".

For example, root names for GTK+ 2.0.1 can look like:

@gtk.org/gtk:2.0.1

the main GTK+ package

@gtk.org/gtk/devel:2.0.1

development headers for GTK+ 2.0.1

@gtk.org/gtk/docs/devhelp:2.0.1

devhelp plugin for the GTK+ 2.0.1 documentation

or if the package was improved:

@gtk.org/gtk:2.0.1:1