This is a listing of the Example1.xaction Action Sequence Document.
In this example, the Action Sequence has 4 inputs: region, from, subject and message-plain. For region, the type is defined as a string; it has a default value of Central and may come from one of two sources; request and session. When the RuntimeContext resolves the region input at runtime, it will first look in the request (most likely an http request.) If it doesn't find it in the request, it will look in the session (most likely the http session.) If it is not available in the session, the default value will be used. The order that the sources are specified in the XML document is the order that they will be searched. The default is always used as a last resort.
The other inputs only specify a default value. This is analogous to hard coding the parameters to a constant value. Since the output of this Action Sequence is an email, no output parameters will be set.