Lock MovieClip horizontally

I have a movie clip that drags on press and stops drag on release

I want to lock it so that it can only move up and down not left and right.

I know you can set it to its original x position on an enterframe but this is messy and jerky. Is there another way to lock it??

Many thanks,

Dravos

use

on (press) {
this.startDrag(true,_x,0,_x,480)
}

on (release) {stopDrag()
}

and modify 0 and 480 as appropriate

sorry for the late response, just saying thanks for the help