diff --git a/timev.rb b/timev.rb
index 5d3af0b559..d3d8b39786 100644
--- a/timev.rb
+++ b/timev.rb
@@ -47,25 +47,30 @@
#
# == \Time Internal Representation
#
-# Time implementation uses a signed 63 bit integer, Integer, or
-# Rational.
-# It is a number of nanoseconds since the _Epoch_.
+# Conceptually, Time class uses a Rational value to represent the number of
+# nanoseconds from _Epoch_, 1970-01-01 00:00:00 UTC.
+# There are no boundary or resolution limitations.
+# The value can be obtaind using Time#to_r.
+#
+# The Time class always uses the Gregorian calendar.
+# I.e. the proleptic Gregorian calendar is used.
+# Other calendars, such as Julian calendar, are not supported.
+#
+# The implementation uses a signed 63 bit integer or Integer (Bignum) to
+# represent the Rational values if possible.
+# (The signed 63 bit integers are used regardless of 32 and 64 bit environments.)
# The signed 63 bit integer can represent 1823-11-12 to 2116-02-20.
# When Integer or Rational is used (before 1823, after 2116, under
# nanosecond), Time works slower than when the signed 63 bit integer is used.
#
# Ruby uses the C function +localtime+ and +gmtime+ to map between the number
# and 6-tuple (year,month,day,hour,minute,second).
-# +localtime+ is used for local time and "gmtime" is used for UTC.
+# +localtime+ is used for local time and +gmtime+ is used for UTC.
#
# Integer and Rational has no range limit, but the localtime and
# gmtime has range limits due to the C types +time_t+ and struct tm.
# If that limit is exceeded, Ruby extrapolates the localtime function.
#
-# The Time class always uses the Gregorian calendar.
-# I.e. the proleptic Gregorian calendar is used.
-# Other calendars, such as Julian calendar, are not supported.
-#
# +time_t+ can represent 1901-12-14 to 2038-01-19 if it is 32 bit signed integer,
# -292277022657-01-27 to 292277026596-12-05 if it is 64 bit signed integer.
# However +localtime+ on some platforms doesn't supports negative +time_t+ (before 1970).
@@ -73,7 +78,7 @@
# struct tm has _tm_year_ member to represent years.
# (tm_year = 0 means the year 1900.)
# It is defined as +int+ in the C standard.
-# _tm_year_ can represent between -2147481748 to 2147485547 if +int+ is 32 bit.
+# _tm_year_ can represent years between -2147481748 to 2147485547 if +int+ is 32 bit.
#
# Ruby supports leap seconds as far as if the C function +localtime+ and
# +gmtime+ supports it.