The basic structure of every xm command is almost always:

  xm <subcommand> <domain-id> [OPTIONS]

Where subcommand is one of the sub commands listed below, domain-id is the numeric domain id, or the domain name (which will be internally translated to domain id), and OPTIONS are sub command specific options. There are a few exceptions to this rule in the cases where the sub command in question acts on all domains, the entire machine, or directly on the xen hypervisor. Those exceptions will be clear for each of those sub commands.