-;; supported. The two other formats are the lists (HIGH LOW) and
-;; (HIGH LOW MICRO). The first two formats specify HIGH * 2^16 + LOW
-;; seconds; the third format specifies HIGH * 2^16 + LOW + MICRO /
-;; 1000000 seconds. We should have 0 <= MICRO < 1000000 and 0 <= LOW
-;; < 2^16. If the time value represents a point in time, then HIGH is
-;; nonnegative. If the time value is a time difference, then HIGH can
-;; be negative as well. The macro `with-decoded-time-value' and the
-;; function `encode-time-value' make it easier to deal with these
-;; three formats. See `time-subtract' for an example of how to use
-;; them.
+;; supported. The other formats are the lists (HIGH LOW), (HIGH LOW
+;; USEC), and (HIGH LOW USEC PSEC). These formats specify the time
+;; value equal to HIGH * 2^16 + LOW + USEC * 10^-6 + PSEC * 10^-12
+;; seconds, where missing components are treated as zero. HIGH can be
+;; negative, either because the value is a time difference, or because
+;; the machine supports negative time stamps that fall before the epoch.
+;; The macro `with-decoded-time-value' and the function
+;; `encode-time-value' make it easier to deal with these formats.
+;; See `time-subtract' for an example of how to use them.