function roll(butNum, suffix) { 
var butName = "button" + butNum; 
butNum --; 
eval("document." + butName + ".src=but" + suffix + "[" + butNum  + "]" + ".src;");

}

function showDateLastMod() { 
// this function gets the last modified date of the calling file and outputs it in a 
// specific format : dd mmmm yyyy hh:nn

var month = new Array(12);   
month[0] = "January";  
month[1] = "Feburary"; 
month[2] = "March";  
month[3] = "April";  
month[4] = "May";  
month[5] = "June";  
month[6] = "July";  
month[7] = "August";  
month[8] = "September";  
month[9] = "October";  
month[10] = "November";  
month[11] = "December";   

var modDate = new Date(document.lastModified);

var dayStr = modDate.getDate();
if (dayStr < 10)
  dayStr = "0" + dayStr;

var monthStr = month[modDate.getMonth()];

var yearStr = modDate.getYear();   
if (yearStr < 2000)
  yearStr = yearStr + 1900;

var hourStr = modDate.getHours();
if (hourStr < 10)
  hourStr = "0" + hourStr;

var minStr = modDate.getMinutes();
if (minStr < 10)
  minStr = "0" + minStr;

var wholeStr = "last modified: " + dayStr + " " + monthStr + " " + yearStr + " - " + hourStr + ":" + minStr; 

document.write(wholeStr);

}