refine language around XCode and gcc versions

Change-Id: I296d18b8192ccdcddcfb2c7288ee61a8240b0ba1
diff --git a/src/source/initializing.md b/src/source/initializing.md
index f6cad96..115d842 100644
--- a/src/source/initializing.md
+++ b/src/source/initializing.md
@@ -137,8 +137,9 @@
 ## Installing required packages ##
 
 - Install XCode from [the Apple developer site](http://developer.apple.com/).
-We recommend version 3.1.4 or newer. If you are not already registered as an
-Apple developer, you will have to create an Apple ID in order to download.
+We recommend version 3.1.4 or newer, i.e. gcc 4.2.
+If you are not already registered as an Apple developer, you will have to
+create an Apple ID in order to download.
 
 - Install MacPorts from [macports.org](http://www.macports.org/install.php).