if (!app.project.file) {
	alert ("This project must be saved before running this script.");
} else {
	var currFile = app.project.file;
	var currFileName = currFile.name;
	var extPos = currFileName.lastIndexOf(".");
	var ext = "";
	
	if (extPos != -1) {
		ext = currFileName.substring(extPos, currFileName.length);
		currFileName = currFileName.substring(0, extPos);
	}
	
	var incrementer = 0;
	if (currFileName.charAt(currFileName.length -4) == "_") {
		//Assume the incrementer has run before if underscore is the fourth character from the end.
		//This is the case for files with 3 digit extensions.
		incrementer = currFileName.substring(currFileName.length - 3, currFileName.length);
		currFileName = currFileName.substring(0, currFileName.length -4);
	}
	
	incrementer++;
	var istring = incrementer + "";
	if( (incrementer / 10) < 1.0) {
		istring = "0" + istring;
	}
	if( (incrementer / 100) < 1.0) {
		istring = "0" + istring;
	}
	
	var newFile = File(currFile.path + "/" + currFileName + "_" + istring + ext);
	alert(newFile.fsName);
	app.project.save(newFile);
}