flash - What is <rs: in Flex/Action Script 3? -

i found

<rs:page>     <mx:image source="@embed('image1.jpg')" />     <mx:label   x="400" y="40" fontfamily="verdana" fontsize="9" color="#cccccc" text="butn" />     <mx:label   left="100" right="120" y="90"  color="#ffccdd" textalign="left" text="label text" /> </rs:page> 

in mxml file. means?

edit: 1

<?xml version="1.0" encoding="utf-8"?> <mx:application     xmlns:mx="http://www.adobe.com/2006/mxml"     xmlns:filters="flash.filters.*"     xmlns:rs="com.mybooks.book.*"     layout="absolute"      backgroundcolor="#333333"      creationcomplete="oncreationcomplete()"      viewsourceurl="source/index.html" width="600" height="330"> 

it means custom namespace prefix rs defined. definition @ beginning of mxml file:

<?xml version="1.0"?> <mx:application    xmlns:mx="http://www.adobe.com/2006/mxml"   xmlns:rs="example.package.name.*" > 

see using xml namespaces

page custom component defined in rs namespace.

in plain actionscript write this:

import com.mybooks.book.page;  private function createpage(): void {     var page: page = new page();     this.addchild(page);     var image: image = new image();     // todo: set image properties      page.addchild(image);     var labela: label = new label();     // todo: set labela properties      page.addchild(labela);     var labelb: label = new label();     // todo: set labelb properties      page.addchild(labelb); }