Isometry Q

1 
for (x = 0; x < 10; x++){
	for (y = 0; y < 10; y++){
		this.createTextField("_txt"+depth, depth, x*20, y*20, 20, 20);
		this_txt = this["_txt"+depth++];
		this_txt.border = true;
		this_txt.text = x+":"+y;
	}

I do not understand in the above why depth is specified as “depth”… and also why is tere x times 20… would that make one table have 0 width, with a 20 height?..

I am reading from this:

http://www.macromedia.com/support/flash/action_scripts/actionscript_dictionary/actionscript_dictionary513.html

&

http://www.kirupa.com/developer/isometric/viewgrid.htm

Thanks!