Updates the README file and includes the NTP standard description, RF…

…C #5905.

README.md

@@ -1,37 +1,57 @@
 # ios-ntp
 
-An application testbed and a network time protocol client for iOS. This is a
-work in progress.
+A network time protocol client and application testbed for iOS.
+This is a continues to be a work in progress.
 
 Created by Gavin Eadie on Oct 17, 2010
 
 ----
-**November 19, 2014:** A large update was made to bring ios-ntp into the modern world.
-The changes do include one bug fix, but are mostly related to making the code comply
-with the recent Xcode changes and requirements.  Such things are sometimes tricky, so
-make sure you test carefully when you adopt today's changes.
-
-Some of jbenet's "Usage" notes below aren't completely accurate as a result of these
-changes, and I will update the text soon.
+**November 19, 2014:** A large update was made today to bring ios-ntp
+into the modern world. The changes do include one bug fix, but are
+mostly related to making the code comply with the recent Xcode changes
+and requirements.  Such things are sometimes tricky, so make sure you
+test carefully when you adopt today's changes.
+
+Some of jbenet's "Usage" notes below aren't completely accurate as a
+result of these changes, and I will update the text soon.
+
+Finally, note that this code was written when there were only 32-bit iOS
+devices. As I write this there are still 32-bit devices which run the
+latest version of iOS (iPhone 4S, for example), but all newer iOS
+devices have a 64-bit architecture (iPhone 6, for example).  Since the
+representation of "Unix time" uses an 'signed long' for seconds since
+Unix epoch (01 Jan 1970), this value rolls over on 19 Jan 2038 on older
+iOS devices.  This is not too worrying, however, since "NTP time" rolls
+over before that, on 08 Feb 2036.  Which is all by way of saying (a) be
+careful with arithmetic, and (b) you should not be using this code in 20
+years, or setting your device's clock past 2038 !!
 
 ----
 ### About
 
-The clock on an iPhone, iTouch or iPad is not closely synchronized to the
-correct time. In the case of a device with access to the telephone system, there
-is a setting to enable synchronizing to the phone company time, but that time
-has been known to be over a minute different from UTC.
+The clock on an older iPhone, iTouch or iPad is not closely synchronized
+to the correct time. In the case of a device which is obtaining its time
+from the telephone system, there is a setting to enable synchronizing to
+the phone company time, but that time has been known to be over a minute
+different from UTC.
 
-In addition, users may change their device time and severely affect applications
-that rely on correct times to enforce functionality.
+In addition, users may change their device time and severely affect
+applications that rely on correct times to enforce functionality.
 
-This project contains code to provide time obtained from standard time servers
-using the network time protocol (NTP: RFCs 4330 and 5905). The implementation is
-not a rigorous as described in those RFCs since the goal was to improve time
-accuracy to within a second, not to fractions of milliseconds.
+This project contains code to provide time obtained from standard time
+servers using the simple network time protocol (SNTP: RFC 5905). The
+implementation is not a rigorous as described in those RFCs since the
+goal was to improve time accuracy to less than a second, not to
+microseconds.
 
 ### This Fork
 
+----
+**November 19, 2014:** jbenet and I (gavineadie) have agreed that I will resume
+taking care of this project and will let the old version at Google Code fade away.
+I've come to enjoy git much more than svn also.
+
+----
 This is a fork from the original source at
 [http://code.google.com/p/ios-ntp/](http://code.google.com/p/ios-ntp/) that
 provides ios-ntp as a *static* iOS framework. This makes its use easier and
@@ -41,17 +61,17 @@ Why fork? Well, because git and github are much more convenient than google code
 for me. I (jbenet) am subscribed to the RSS feed of the original project and
 will merge any upstream changes.
 
-jbenet and I (gavineadie) have agreed that I will resume taking care of this project
-and will let the old version at Google Code fade away.  I've come to enjoy git much
-more than svn also.
-
 ### License
 
 The [MIT](http://www.opensource.org/licenses/mit-license.php) License
 Copyright (c) 2010-4, Ramsay Consulting
 
 ### Usage
 
+----
+**November 19, 2014:** Some of the words below are not true.  That will be fixed soon.
+
+----
 Download [ios-ntp.tar.gz](https://raw.github.com/jbenet/ios-ntp/master/release/ios-ntp.tar.gz),
 and add `ios-ntp.framework` to your project. Make sure the file `ntp.hosts` is
 added to the project. I should show within the ios-ntp.framework/Headers
@@ -65,7 +85,7 @@ Edit ntp.hosts to add or remove any NTP servers. Make sure it is OK to use them.
 
 Then, simply call:
 
-    [NSDate networkDate];
+[NSDate networkDate];
 
 As soon as you call it, the NTP process will begin. If you wish to start it at
 boot time, so that the time is well synchronized by the time you actually want
@@ -80,6 +100,4 @@ Resources directory of frameworks.
 
 To build the static framework, build the `ios-ntp` target from the xcode
 project. Make sure you build BOTH the `iPhone Simulator` and `iOS Device`
-architectures.
-
-
+architectures.