//Workaround da sonst indexOf => undefined geliefert wird 
//IF INDD CC: #targetengine com.adobe.DesignLibraries.angular_Engine_Id   
Array.prototype.indexOf = function ( item ) {   
              var index = 0, length = this.length;   
              for ( ; index < length; index++ ) {   
                        if ( this[index] === item )   
                                  return index;   
              }   
              return -1;   
              };   
 
var _myDoc = app.activeDocument; 
 
app.findGrepPreferences = app.changeGrepPreferences = null; 
app.changeGrepPreferences = null; 
app.findGrepPreferences.findWhat = '.+'; 
app.findGrepPreferences.appliedCharacterStyle = 'EN_Target'; 
var _Result = _myDoc.findGrep(); 
var _SelectPos = app.selection[0]; 
var StartNum = _Result.indexOf(_SelectPos); 
 
var _mySelectLetter = app.selection[0].contents; 
var _myChars = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]; 
var _myString = _myChars.indexOf(_mySelectLetter); 
var _Counter = _myString; 
 
for(var i = StartNum; i < _Result.length; i++) { 
//for(var i = 0; i < _Result.length; i++) { 
     if (_Counter === 26)  { 
         var _Counter = 0; 
           } 
      _Result[i].contents = _myChars[_Counter];  
      _Counter++; 
}