System.Security.SecurityElement.IsValidText C# (CSharp) Method

        public static bool IsValidText(string text)
        {
            if (text == null)
                return false;

            return text.IndexOfAny(s_textIllegalCharacters) == -1;
        }

 /// <summary>用指定的标记和文本初始化 <see cref="T:System.Security.SecurityElement" /> 类的新实例。</summary>
 /// <param name="tag">XML 元素的标记名称。</param>
 /// <param name="text">元素中的文本内容。</param>
 /// <exception cref="T:System.ArgumentNullException">
 /// <paramref name="tag" /> 参数为 null。</exception>
 /// <exception cref="T:System.ArgumentException">
 /// <paramref name="tag" /> 参数或 <paramref name="text" /> 参数在 XML 中无效。</exception>
 public SecurityElement(string tag, string text)
 {
     if (tag == null)
     {
         throw new ArgumentNullException("tag");
     }
     if (!SecurityElement.IsValidTag(tag))
     {
         throw new ArgumentException(string.Format((IFormatProvider)CultureInfo.CurrentCulture, Environment.GetResourceString("Argument_InvalidElementTag"), (object)tag));
     }
     if (text != null && !SecurityElement.IsValidText(text))
     {
         throw new ArgumentException(string.Format((IFormatProvider)CultureInfo.CurrentCulture, Environment.GetResourceString("Argument_InvalidElementText"), (object)text));
     }
     this.m_strTag  = tag;
     this.m_strText = text;
 }