charBefore = "[";
charAfter = "]";
strSelectedText = document.selection.Text;

document.selection.Text = charBefore + strSelectedText + charAfter;

#title = "Enclose selection";
#tooltip = "Enclose an selection with an sign";
// Select some text and execute this macro to put an sign 
// in front and at the end of the selected text;

//mySign = "%"
  mySign =  prompt( "Enter sign to enclose selection:", "%" );

  selText = document.selection.Text;
  outText = mySign + selText + mySign;


  //alert(outText);
  document.selection.Text = outText;