Zip format compatibility improvements and bug fixes. Specifically, compatibility with older zip tools has been increased by making it the default behavior to produce Zip 2.0-compatible archives; this behavior can be changed by the developer. Also, the ZipWriter can generate uncompressed zip files that the product's ZipReader can read increasing flexibility (combines the Deflate format and no compression).

(The corresponding .NET 3.5 version for this release is v4.3.)