'Format an external-command downtime deletion string.
cmd - Nagios command ID
host - Host to remove scheduled downtime from
comment - Reason downtime was added (upgrade, reboot, etc)
start - Start of downtime in seconds since 12:00AM Jan 1 1970
svc - Service to remove downtime for, omit to remove all downtime for the host
Syntax: [submitted] COMMAND;<host_name>;
[<service_desription>];[<start_time>];[<comment>]'

def _fmt_dt_del_str(self, cmd, host, svc=None, start=None, comment=None):

    entry_time = self._now()
    hdr = ('[%s]    %s;%s;' % (entry_time, cmd, host))
    if (comment is None):
        comment = self.comment
    dt_del_args = []
    if (svc is not None):
        dt_del_args.append(svc)
    else:
        dt_del_args.append('')
    if (start is not None):
        dt_del_args.append(str(start))
    else:
        dt_del_args.append('')
    if (comment is not None):
        dt_del_args.append(comment)
    else:
        dt_del_args.append('')
    dt_del_arg_str = ';'.join(dt_del_args)
    dt_del_str = ((hdr + dt_del_arg_str) + '\n')
    return dt_del_str
