static void
check(long i) {
	if (i < 0 || i > MAX_VALUE)
		throw new InvalidTTLException(i);
}
Routines for parsing BIND-style TTL values.  These values consist of
numbers followed by 1 letter units of time (W - week, D - day, H - hour,
M - minute, S - second).

@author Brian Wellington
src/main/java/core/org/xbill/DNS/TTL.java