Help with Acrobat Javascript Shared Functions

This is not clear in the Javascript document, but where can I put shared functions which are used by my scripts?

Below I have 3 functions.  X() and Z() which should both happen on the blur of a text field.

Function Y() is a calculation which both X() and Z() need to use.

Y is available for X(), but not for Z() without pasting its code twice.

Where do shared functions go?

//-------------------------------------------------------------
//-----------------Do not edit the XML tags--------------------
//-------------------------------------------------------------
 
 
//<AcroForm>
//<ACRO_source>CN1:Annot1:OnBlur:Action1</ACRO_source>
//<ACRO_script>
/*********** belongs to: AcroForm:CN1:Annot1:OnBlur:Action1 ***********/
function X()
{
              int x = 0;
              //do something
              int y = Y();  //Works here
    return x;
}
 
function Y() 
{
              int y = 1;
              //do something
    return Y;
}
 
//</ACRO_script>
//</AcroForm>
 
 
//<AcroForm>
//<ACRO_source>CN2:Annot1:OnBlur:Action1</ACRO_source>
//<ACRO_script>
/*********** belongs to: AcroForm:CN2:Annot1:OnBlur:Action1 ***********/
 
function Z() 
{
              int Z = 2;
              //do something
              int y = Y(); //Function Y is out of scope/unavailable here
    return Z;
}
 
//</ACRO_script>
//</AcroForm>