Instructions on how to use the online tool: 


1) Loading IFSignatures Dynamically - Example 

The program: 
var h; 
h = 2; 
upgVar(h, '2'); 
alert(h); 

Is illegal according to the default program for alert 
(a program cannot alert sensitive content). However, 
it the following IFSignature is loaded: 

_enforce = function (lev_ctxt, f, arg, lev_arg) {
}; 

_updtLab = function (ret,  lev_ctxt, f, arg, lev_arg) {
      return lev_ctxt; 
};
 
_isInDomain = function (f, prop, fun_flag) {
        return (fun_flag === 'function_call') && (f === alert) && (prop === null); 
};

The program above will become legal.


2) I introduce two special upgrade instructions that are needed. 
  
   2.1) upgTreeLevel - upgrades the ownIndex property of a node (together with its
        pNode property and with the index property that points to it). But first, 
        it checks if the invariant concerning the levels of the indexes of a DOM 
        Element Node is still verified. 

   2.2) upgGlobalTagLevel(TAG, LEVEL) - upgrades the level corresponding to the 
        upper threshold on the levels of the context in which nodes with tag TAG
        can be appended or removed. 
        
3)