Updating Flash 4 Actionscript

I’ve got a file that I’m modifying for use in a new Flash movie I’m making. The trouble is, it was made in Flash 4 so the ActionScript is old and a little harder for me to understand since I’ve only been using Flash since version 5.

When opening the file in Flash MX 2004, Flash did update some of the code for me, but this code is still old:

if (Number(getProperty("/textbox", _y))>=Number(/:original_y)) {
gotoAndPlay("stop");
} else {
setProperty("/textbox", _y, Number(getProperty("/textbox", _y))+20);
setProperty("/slider", _y, Number((-(((getProperty("/textbox", _y))/(/slider:multiplier)))))+Number((/slider:slider_area)));
}

Now, I assume the “/textbox” should be changed to _parent.textbox, and the same with the “/slider”, but what about this: /:original_y ??

I’ve never come across /: before and don’t understand what it means or does, nor do I know what the new Actionscript code is to achieve this. Can anyone help? Thanx