#target bridge    
   if( BridgeTalk.appName == "bridge" ) {   
setExposure = MenuElement.create("command", "Set Average Exposures", "at the end of Tools","exp"); 
} 
setExposure.onSelect = function () { 
var d=app.document; 
d.deselectAll(); 
var sels = d.getSelection("cr2,crw,nef,mos,orf"); 
var noOfFiles =sels.length; 
var diff = (3.25 / (noOfFiles-1)); 
var exp = 1.25; 
var exp2=exp; 
for(var a = 0;a<noOfFiles;a++){ 
    exp2 = exp - (diff*(a)).toFixed(3); 
    var file = new File(sels[a].spec.toString().replace(/\....$/,'.xmp')); 
    setExposure( file, exp2 ) 
    } 
app.document.chooseMenuItem('PurgeCache'); 
function setExposure( file, expose ){ 
     file.open('r'); 
     file.encoding = "UTF8"; 
     file.lineFeed = "unix";  
     file.open("r", "TEXT", "????"); 
     var xmpStr = file.read(); 
     file.close(); 
     if (ExternalObject.AdobeXMPScript == undefined) ExternalObject.AdobeXMPScript = new ExternalObject("lib:AdobeXMPScript"); 
     var xmp = new XMPMeta( xmpStr ); 
     xmp.setProperty( XMPConst.NS_CAMERA_RAW, "Exposure", Number(expose) ); 
     file.open('w'); 
     file.encoding = "UTF8"; 
     file.lineFeed = "unix";  
     file.write( xmp.serialize() ); 
     file.close(); 
    }; 
}; 

XMPMeta.registerNamespace("http://ns.adobe.com/camera-raw-saved-settings/1.0/","crss"); 
 
myXMPObj.setProperty("http://ns.adobe.com/camera-raw-saved-settings/1.0/","crss:SavedSettings/rdf:Bag/rdf:li/crss:Name","My Snapshot",0); 
myXMPObj.setProperty("http://ns.adobe.com/camera-raw-saved-settings/1.0/","crss:SavedSettings/rdf:Bag/rdf:li/crss:Type","Snapshot",0); 

XMPUtils.duplicateSubtree(myXMPObj,myXMPObj,"http://ns.adobe.com/camera-raw-settings/1.0/","crs:Version","http://ns.adobe.com/camera-raw-saved-settings/1.0/","crss:SavedSettings/rdf:Bag/rdf:li/crss:Parameters/crs:Version",XMPConst.APPEND_ALL_PROPERTIES);