That tab is so for whatever reason the transmission locks up and wont come out of park. Just pop that cover, put the key in, turn it and shift to nuetral. then start the car in neutral and then shift the car to whatever gear you want. After that it should be unlocked and can go back to shifting it as you were. Sometimes the system will lock up and you have to use this to unlock it. The Old Chevrolet Aveo's had this feature. My brothers aveo had locked up several times and wouldnt come out of park and once he did what i stated, it would shift again. Hope this helps you all out.