When you are in sketch mode in Pro-E, you can always make use of "references".It is very handy and easy to use.You don't need to remember every dimensions of the part from the axes or origin of your drawing.
Its very basic thing one learns while learning pro-e.
Solidworks has flexibility of dimensioning unlike Pro-e.
But pro-e has a very cool way of adding more segments to the existing part by using
References is used in sketcher mode only.It lets you use existing geometry in a better way.By adding references , sometimes you can resolve the unresolved sketches also.
Any suggestions and questions are welcome...
Answered with a tutorial: https://grabcad.com/tutorials/tutorial-how-to-save-time-in-sketcher-mode-in-pro-e-creo-elements