diff --git a/Cargo.toml b/Cargo.toml
index 2a11f61..19d2226 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "chrono"
-version = "0.2.1"
+version = "0.2.2"
 authors = ["Kang Seonghoon <public+rust@mearie.org>"]
 
 description = "Date and time library for Rust"
@@ -15,5 +15,5 @@ license = "MIT/Apache-2.0"
 name = "chrono"
 
 [dependencies]
-time = "0.1.17"
+time = "0.1.19"
 
diff --git a/README.md b/README.md
index 661cadf..783fc69 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-[Chrono][doc] 0.2.1
+[Chrono][doc] 0.2.2
 ===================
 
 [![Chrono on Travis CI][travis-image]][travis]
@@ -224,7 +224,7 @@ assert_eq!(UTC.ymd(2014, 11, 28).and_hms_milli(7, 8, 9, 10).format("%H%M%S").to_
 
 There is no timezone-aware `Time` due to the lack of usefulness and also the complexity.
 
-`DateTime` has `date` method which returns a narrow view to its date component.
+`DateTime` has `date` method which returns a `Date` which represents its date component.
 There is also a `time` method, which simply returns a naive local time described below.
 
 ### Naive date and time
diff --git a/src/lib.rs b/src/lib.rs
index a0f1838..806ddca 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,7 +4,7 @@
 
 /*!
 
-# Chrono 0.2.1
+# Chrono 0.2.2
 
 Date and time handling for Rust. (also known as `rust-chrono`)
 It aims to be a feature-complete superset of the [time](https://github.com/rust-lang/time) library.
@@ -226,7 +226,7 @@ assert_eq!(UTC.ymd(2014, 11, 28).and_hms_milli(7, 8, 9, 10).format("%H%M%S").to_
 
 There is no timezone-aware `Time` due to the lack of usefulness and also the complexity.
 
-`DateTime` has `date` method which returns a narrow view to its date component.
+`DateTime` has `date` method which returns a `Date` which represents its date component.
 There is also a `time` method, which simply returns a naive local time described below.
 
 ### Naive date and time
diff --git a/src/offset/mod.rs b/src/offset/mod.rs
index 509b2e0..ef2b65c 100644
--- a/src/offset/mod.rs
+++ b/src/offset/mod.rs
@@ -165,6 +165,9 @@ pub trait Offset: Sized + Clone + fmt::Debug {
 
 /// The time zone.
 pub trait TimeZone: Sized {
+    /// An associated offset type.
+    /// This type is used to store the actual offset in date and time types.
+    /// The original `TimeZone` value can be recovered via `TimeZone::from_offset`.
     type Offset: Offset;
 
     /// Makes a new `Date` from year, month, day and the current time zone.