(flexTFS, p. 20). Inside the <mx:Application>tag, the attribute/value pair that appears to hold a URL xmlns:mx=“http://www.adobe.com/2006/mxml” is defining a namespace for your Flex tags.[…]. In a configuration file (flex-config.xml), an associtaion is made between this URI and what is called a manifest file. In a standard installation, the file is found at installationdirec/flex_sdk_2/frameworks/mxml-manifest.xml.
Style explorer @adobe.examples
Unit Testing with ASunit @insideria
The list of helpful Flex or Flash debug tools @saravananrk
List of 22 ActionScript 3.0 API’s @saravananrk
Building and Deploying Flex Applications @ livedocs.adobe.com
Code Repository @ onflex.org
Flex Cookbook Beta @ adobe.com
The Flex Non-Docs. For all those secrets in Flex, those that aren't known, those that aren't published, or those that are just hard to find for some unknown reason, like percentWidth.
Flex 2 Language Reference @ adobe.com