diff --git a/lib/tzinfo/time_or_datetime.rb b/lib/tzinfo/time_or_datetime.rb
index 91938b4e..e36a0521 100644
--- a/lib/tzinfo/time_or_datetime.rb
+++ b/lib/tzinfo/time_or_datetime.rb
@@ -9,8 +9,8 @@ class TimeOrDateTime
     include Comparable
 
     # Constructs a new TimeOrDateTime. timeOrDateTime can be a Time, DateTime
-    # or Integer. If using a Time or DateTime, any time zone information
-    # is ignored.
+    # or Integer. The UTC offset from Time or DateTime instances is ignored
+    # unless ignore_offset is set to false.
     def initialize(timeOrDateTime, ignore_offset = true)
       @time = nil
       @datetime = nil
@@ -198,8 +198,7 @@ def usec
       end
     end
 
-    # Returns utc offset of original value _in seconds_ (or 0 if original
-    # value was integer timestamp).
+    # Returns the UTC offset of this TimeOrDateTime in seconds.
     def offset
       if @time
         @time.utc_offset
@@ -270,20 +269,24 @@ def -(seconds)
       self + (-seconds)
     end
 
-    # Converts TimeOrDateTime to new UTC offset.
-    # Considers original value's UTC offset wisely.
-    def to_offset(seconds)
+    # For TimeOrDateTime instances based on Time or DateTime values, returns a
+    # new TimeOrDateTime created by adjusting the UTC offset to the given
+    # offset in seconds.
+    #
+    # For TimeOrDateTime instances based on Integer timestamps, returns a new
+    # TimeOrDateTime created by adding the given offset to the timestamp.
+    def to_offset(offset)
       if @orig.is_a?(DateTime)
-        off = OffsetRationals.rational_for_offset(seconds)
+        off = OffsetRationals.rational_for_offset(offset)
         TimeOrDateTime.new(@orig.new_offset(off), false)
       elsif @orig.is_a?(Time)
-        time = @time.getutc + seconds
+        time = @time.getutc + offset
         nsec_part = Rational(time.nsec, 1_000_000_000)
-        time = Time.new(time.year, time.mon, time.mday, time.hour, time.min, time.sec + nsec_part, seconds)
+        time = Time.new(time.year, time.mon, time.mday, time.hour, time.min, time.sec + nsec_part, offset)
         TimeOrDateTime.new(time, false)
       else
         # Integer: fallback to "just shift timestamp"
-        TimeOrDateTime.new(@orig + seconds)
+        TimeOrDateTime.new(@orig + offset)
       end
     end
 
@@ -311,11 +314,10 @@ def hash
     # will be constructed and the value passed to wrap will be used when
     # calling the block.
     #
-    # Optional ignore_offset second parameter (defaults to true) controls
-    # whether timezone/UTC offset of input value will be considered or
-    # ignored completely (in a latter case `2016-06-01 12:30:50 +03:00`
-    # and `2016-06-01 12:30:50 GMT` would be wrapped into exactly the
-    # same `TimeOrDateTime` object).
+    # The UTC offset from Time or DateTime instances is ignored unless
+    # ignore_offset is set to false (for example, 2016-06-01 12:30:50 +03:00
+    # and 2016-06-01 12:30:50 GMT would be wrapped into exactly the same
+    # TimeOrDateTime object when ignore_offset is true).
     def self.wrap(timeOrDateTime, ignore_offset = true)
       t = timeOrDateTime.is_a?(TimeOrDateTime) ? timeOrDateTime : TimeOrDateTime.new(timeOrDateTime, ignore_offset)
 
diff --git a/lib/tzinfo/timezone.rb b/lib/tzinfo/timezone.rb
index 2a691dbb..7d2c8cbb 100644
--- a/lib/tzinfo/timezone.rb
+++ b/lib/tzinfo/timezone.rb
@@ -266,14 +266,20 @@ def friendly_identifier(skip_first_part = false)
 
     # Returns the TimezonePeriod for the given UTC time. utc can either be
     # a DateTime, Time or integer timestamp (Time.to_i). Any timezone
-    # information in utc is ignored (it is treated as a UTC time).
+    # information in utc is ignored (it is treated as a UTC time). Use the
+    # period_for method instead if the the UTC offset of the time needs to be
+    # considered.
     def period_for_utc(utc)
       raise_unknown_timezone
     end
 
     # Returns the set of TimezonePeriod instances that are valid for the given
-    # local time as an array. If you just want a single period, use
-    # period_for_local instead and specify how ambiguities should be resolved.
+    # local time as an array. Any timezone information in local is ignored
+    # (it is treated as a time in the current timezone).
+    #
+    # If you just want a single period, use period_for_local instead and specify
+    # how ambiguities should be resolved.
+    #
     # Returns an empty array if no periods are found for the given time.
     def periods_for_local(local)
       raise_unknown_timezone
@@ -347,7 +353,8 @@ def canonical_zone
     # Returns the TimezonePeriod for the given local time. local can either be
     # a DateTime, Time or integer timestamp (Time.to_i). Any timezone
     # information in local is ignored (it is treated as a time in the current
-    # timezone).
+    # timezone). Use the period_for method instead if the the UTC offset of the
+    # time needs to be considered.
     #
     # Warning: There are local times that have no equivalent UTC times (e.g.
     # in the transition from standard time to daylight savings time). There are
@@ -418,32 +425,32 @@ def period_for_local(local, dst = Timezone.default_dst)
       end
     end
 
-    # Returns the TimezonePeriod for the given local time. local can either be
-    # a DateTime, Time or integer timestamp (Time.to_i). Unlike `period_for_local`,
-    # actually considers timezone information of local, thus eliminating
-    # all complexities about AmbiguousTime.
+    # Returns the TimezonePeriod for the given time. time can either be
+    # a DateTime, Time or integer timestamp (Time.to_i).
     #
-    def period_for(local)
-      # FIXME: maybe define TimeOrDateTime#to_utc as a synonym for #to_offset(0)?..
-      period_for_utc(TimeOrDateTime.wrap(local, false).to_offset(0))
+    # Unlike period_for_local and period_for_utc, period_for considers the UTC
+    # offset of the given time.
+    def period_for(time)
+      period_for_utc(TimeOrDateTime.wrap(time, false).to_offset(0))
     end
 
     # Converts a time in UTC to the local timezone. utc can either be
     # a DateTime, Time or timestamp (Time.to_i). The returned time has the same
     # type as utc. Any timezone information in utc is ignored (it is treated as
-    # a UTC time).
+    # a UTC time). Use the to_local method instead if the the UTC offset of the
+    # time needs to be considered.
     def utc_to_local(utc)
       TimeOrDateTime.wrap(utc) {|wrapped|
         period_for_utc(wrapped).to_local(wrapped)
       }
     end
 
-    # Converts a time in some local timezone to another local timezone.
-    # another_local can either be a DateTime, Time or timestamp (Time.to_i).
+    # Converts a time to the local timezone. time can either be a DateTime, Time
+    # or timestamp (Time.to_i).
     #
-    # Considers timezone of another_local.
-    def to_local(another_local)
-      TimeOrDateTime.wrap(another_local, false) {|wrapped|
+    # Unlike utc_to_local, to_local considers the UTC offset of the given time. 
+    def to_local(time)
+      TimeOrDateTime.wrap(time, false) {|wrapped|
         period_for(wrapped).to_local(wrapped)
       }
     end