-lifetime of Exim. This description was rewritten for Exim 4.14 (February 2003).
-Retaining all the history in the comment has become too unwieldy - read
-previous release sources if you want it.
-
-The message ID has 3 parts: tttttt-pppppp-ss. Each part is a number in base 62.
-The first part is the current time, in seconds. The second part is the current
-pid. Both are large enough to hold 32-bit numbers in base 62. The third part
-can hold a number in the range 0-3843. It used to be a computed sequence
-number, but is now the fractional component of the current time in units of
-1/2000 of a second (i.e. a value in the range 0-1999). After a message has been
-received, Exim ensures that the timer has ticked at the appropriate level
-before proceeding, to avoid duplication if the pid happened to be re-used
-within the same time period. It seems likely that most messages will take at
-least half a millisecond to be received, so no delay will normally be
-necessary. At least for some time...
+lifetime of Exim, and is changing for Exim 4.97.
+The previous change was in about 2003.
+
+Detail for the pre-4.97 version is here in [square-brackets].
+
+The message ID has 3 parts: tttttt-ppppppppppp-ssss (6, 11, 4 - total 23 with
+the dashes). Each part is a number in base 62.
+[ tttttt-pppppp-ss 6, 6, 2 => 16 ]