So what if yo were given "...descend FL100, cross ABCD FL 140" and than later on given radar vector some 10, 20 degrees left or right (maybe even present hdg). Sometimes these restrictions are quite low from pilot's point and for saving the fuel - higher the better.
Also on SID: Cross ABCD FL 100 or bellow, and ATC clears you FL 130 in Clearance pre Taxi, and than after take-off with Departure ATC "... Climb FL 150" Are we to maintain FL 100 up to the ABCD until clear higher by Departure ATC?
Is there a book or something on the matter?
Thanks.