[Answered] i would like to know what is this in x3 ?

 dynamic content location presets

Content location presets are the presets that you see in SONAR's  Media browser, eg Loops, MIDI groove clips, etc. Most content location presets are shortcuts to static folder paths on your computer.
Dynamic presets on the other hand refer to presets for locations that might change. For example,  the new "Project Audio" preset in the browser will point to the project audio folder for the currently open project (or the global audio folder if it isn't a per project audio project). IOW the actual location varies based on the project. 
Project audio is like a media bin for your project audio...
 
In X3 both static and dynamic content location presets will update automatically if the folder content changes, unlike X2.