https://dotnetframework.org/default.aspx/Dotnetfx_Vista_SP2/Dotnetfx_Vista_SP2/8@0@50727@4016/DEVDIV/depot/DevDiv/releases/whidbey/NetFxQFE/ndp/fx/src/Xml/System/Xml/schema/DtdParser@cs/1/DtdParser@cs
DtdParser.cs source code in C# .NET
cs sourcecode