un lang talaga..its just like in your manal tranny...

when you put in L or 1 or D1 or manual mode in 1-->1st gear in your manual
when you put in 2 or D2 or manual mode in 2-->2nd gear in your manual
when you put in D, turn off the overdrive or D3 or manual mode in 3-->3rd gear in your manual, etc

un ung common sa lahat ng tranny, ang difference lang is ung iba my D3, and manual mode...pero pag D(with Overdrive on) all gears will go..

pag electronically-controlled a/t, may grade-logic systems, di mo na ganu kailang ishift pa ung lever...ung iba may "hold" button..i-on mo un, they say it hold the gear position where it was pushed (without letting a downshift on the tranny)