This Analytics Edge wizard is used to select a predefined Google Analytics segment from your account, or to define a dynamic one to be used solely for this query.
All system-provided segments are listed first, followed by your custom segments, alphabetically sorted.
When you select DYNAMIC from the drop-down, you can enter a segment expression in the text box below. Any expression can be entered — click the reference link in the wizard to open the Google Analytics API reference guide for segments.