-is the number of seconds from the @dfn{epoch} (0:00 January 1, 1970
-UTC) to the specified time. The third list element @var{microsec}, if
-present, gives the number of microseconds from the start of that
-second to the specified time.
-Similarly, the fourth list element @var{picosec}, if present, gives
-the number of picoseconds from the start of that microsecond to the
-specified time.
-
- The return value of @code{current-time} represents time using four
-integers, as do the timestamps in the return value of
-@code{file-attributes} (@pxref{Definition of
-file-attributes}). In function arguments, e.g., the @var{time-value}
-argument to @code{current-time-string}, two-, three-, and four-integer
-lists are accepted. You can convert times from the list
-representation into standard human-readable strings using
-@code{current-time-string}, or to other forms using the
-@code{decode-time} and @code{format-time-string} functions documented
-in the following sections.
+The return value of @code{current-time} represents time using this
+form, as do the timestamps in the return values of other functions
+such as @code{file-attributes} (@pxref{Definition of
+file-attributes}). In some cases, functions may return two- or
+three-element lists, with omitted @var{microsec} and @var{picosec}
+components defaulting to zero.
+
+@cindex time value
+ Function arguments, e.g., the @var{time-value} argument to
+@code{current-time-string}, accept a more-general @dfn{time value}
+format, which can be a list of integers as above, or a single number
+for seconds since the epoch, or @code{nil} for the current time. You
+can convert a time value into a human-readable string using
+@code{current-time-string} and @code{format-time-string}, into a list
+of integers using @code{seconds-to-time}, and into other forms using
+@code{decode-time} and @code{float-time}. These functions are
+described in the following sections.