function insertText(chrField, chrValue) {
    var objField = document.getElementById(chrField);
    if (document.selection) {
        objField.focus();
        sel = document.selection.createRange();
        sel.text = chrValue;
    }
    else if (objField.selectionStart || objField.selectionStart == '0') {
        var startPos = objField.selectionStart;
        var endPos = objField.selectionEnd;
        objField.value = objField.value.substring(0, startPos) + chrValue + objField.value.substring(endPos, objField.value.length);
    } else {
        objField.value += chrValue;
    }
    objField.focus();
}