Disable edit on fields on a SharePoint form

<SCRIPT language=javascript>
function DisableField(title)
{
    for(var i = 0; i < document.all.length; i++)
    {
        var el = document.all[i];
        if(el.title == title)
        {
            el.readOnly = true;
            break;
        }
    }
}
DisableField("Bay");
DisableField("Pos");
DisableField("Status");
</SCRIPT>