function code(campo,code)
{
    var textarea = document.getElementById(campo);

    if(document.selection)
    {
        // IE
        var str = document.selection.createRange().text;
        textarea.focus();
        var sel = document.selection.createRange();
        if(code == 'a'){sel.text = "[" + code + "=' http:// ']" + str + "[/" + code + "]";}
        else{sel.text = "[" + code + "]" + str + "[/" + code + "]";}
    }
    else if(textarea.selectionStart)
    {
        // MOZILLA/NETSCAPE
        var startPos = textarea.selectionStart;
        var endPos = textarea.selectionEnd;
        if(code == 'a'){textarea.value = textarea.value.substring(0,startPos) + "[" + code + "=' http:// ']" + textarea.value.substring(startPos,endPos) + "[/" + code + "]" + textarea.value.substring(endPos,textarea.value.length);}
        else{textarea.value = textarea.value.substring(0,startPos) + "[" + code + "]" + textarea.value.substring(startPos,endPos) + "[/" + code + "]" + textarea.value.substring(endPos,textarea.value.length);}
    }
    else
    {
        if(code == 'a'){textarea.value += "[" + code + "=' http:// '][/" + code + "]";}
        else{textarea.value += "[" + code + "][/" + code + "]";}
    }
}