bName = navigator.appName;
bVersn = parseInt(navigator.appVersion);
versn = "vNOT";
if (bName == "Netscape" && bVersn >= 3) versn = "vOK";
if (bName == "Microsoft Internet Explorer" && bVersn >= 4) versn = "vOK";
if (bName == "Opera" && bVersn >= 5) versn = "vOK";

if (versn != "vNOT") {
mbut1a=new Image(); mbut1a.src="imgmain/grmnu01a.gif";
mbut1b=new Image(); mbut1b.src="imgmain/grmnu01b.gif";
mbut2a=new Image(); mbut2a.src="imgmain/grmnu02a.gif";
mbut2b=new Image(); mbut2b.src="imgmain/grmnu02b.gif";
mbut3a=new Image(); mbut3a.src="imgmain/grmnu03a.gif";
mbut3b=new Image(); mbut3b.src="imgmain/grmnu03b.gif";
mbut4a=new Image(); mbut4a.src="imgmain/grmnu04a.gif";
mbut4b=new Image(); mbut4b.src="imgmain/grmnu04b.gif";
} else {
mbut1a=""; mbut1b=""; mbut2a=""; mbut2b=""; mbut3a=""; mbut3b=""; mbut4a=""; mbut4b=""; }

function chM(imgnum, imgsrc) {
    if (versn == "vNOT") return false;
	document.images['mbut'+imgnum].src=imgsrc.src;
	return true;}