What's mean with the define like "[APPIMG]"

[zhdie]

There are many src define in the example like:
src:"[APPIMG]imgButton/button.gif",
But I can't find the define of the path "[APPIMG]", I use the smartclient just now, couldn't you tell me what's mean with this, thanks.
For example, what's the src of button.gif?

ImgButton.create({
ID:"b2",
left:140,
top:80,
width:33,
height:33,
src:"[APPIMG]imgButton/button.gif",
click:"showClicked(this.getID())",
disabled:true
});

[zhdie]

problem is solved.