More Information about:
Link: 1) http://www.onlinetradingconcepts.com/TechnicalAnalysis/MovingAverageEnvelopes.html

Source Code "Envelopes":

function init()
{
   Envelopes.createParameter("Period", 14);
   Envelopes.createParameter("Shift", 0);
   Envelopes.createParameter("Devitation", 8.5);

   Envelopes.createBuffer("EnvelopesUpper");
   Envelopes.setBufferColor("EnvelopesUpper", "lime");
   Envelopes.setBufferDrawStyle("EnvelopesUpper", DrawStyle.LINE);

   Envelopes.createBuffer("EnvelopesLower");
   Envelopes.setBufferColor("EnvelopesLower", "red");
   Envelopes.setBufferDrawStyle("EnvelopesLower", DrawStyle.LINE);

   Envelopes.setAutoChangeMaxMin("EnvelopesUpper", "EnvelopesLower");
}

function start()
{
   Envelopes.label = "Envelopes(" + Envelopes.parameter("Period")
          + "," + Envelopes.parameter("Shift")
          + "," + Envelopes.parameter("Devitation") + ")";

   var smaBuf =
     Shared.sma(Envelopes.parameter("Period"), Shared.close());

   var devitation = Envelopes.parameter("Devitation");

   var num = Shared.numberOfQuotes();
   var upperBuf = new Array(num);
   var lowerBuf = new Array(num);
   for (var i = 0; i < num; ++i) {
     upperBuf[i] = smaBuf[i] * (1 + devitation / 100);
     lowerBuf[i] = smaBuf[i] * (1 - devitation / 100);
   }

   Envelopes.setBufferData("EnvelopesUpper", upperBuf);
   Envelopes.setBufferData("EnvelopesLower", lowerBuf);
}