of Web clients such as browsers have "generally" failed to follow Bos’ guidance. Starting with PURLz 1.0 series, the PURL service implements partial redirections inclusive of fragment identifiers by writing fragments onto target URLs in an attempt to comply with and avoid problematic and inconsistent behavior by browser vendors. See also Implementation examples: Archival Resource Key (ARK) Digital Object Identifier (DOI) Handle System identifiers Link rot OPAC Permalink URL redirection URL shortening Uniform Resource Name (URN) Wayback Machine References External links Official website for PURLz Official website for The Callimachus Project Internet Archive's PURL resolver US Government Printing Office's PURL resolver persistent-identifier.de DPE/PURL Information and Resolver Site URI schemes Identifiers 1995 software Free software programmed in Java (programming language) Cross-platform free software History of the Internet Internet software for Linux Unix Internet software