Because the GZip compression format only supports the Deflate compression method, all data compressed with the GZipCompressedStream class will be compressed using the Deflated compression method.
If the inner stream is read-only, the compressed stream will read the header at construction.
The compression level only applies to the Deflated and Deflated64 compression methods. It does not apply to the BZip2, BWT, or PPMd compression methods.
Requirements
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2