Editing SCO–SGI code dispute of 2003 (section)

==Origin==
It is possible that the code contributed to Linux originated from [[UNIX System V]], but its original implementation happened in the early 1970s. There are no substantial differences between the original Unix source code and the UNIX System V source. [[Dennis Ritchie]], one of the creators of Unix, acknowledged that either he or [[Ken Thompson]] wrote the original code from which the UNIX System V code is derived:

{{blockquote|So: either Ken or I wrote it originally. I know that the comments that first appeared by the 6th edition were definitely written by me, since I spent some time annotating the almost comment-free earlier editions.}}

This is very important, because early Unix source code does not have any copyright claim. At that time, the law required explicit copyright claims,<ref>{{cite web  | url=http://www.copyright.cornell.edu/resources/publicdomain.cfm  | title=Copyright Term and the Public Domain in the United States  | accessdate=2009-12-04  | date=2009-01-01  | publisher=Cornell }}</ref> which effectively means the early Unix code is not protected by copyright law. Additionally, both [[Santa Cruz Operation]] and The SCO Group released the source code of early versions of Unix<ref>{{cite web  | url=http://www.mckusick.com/csrg/calder-lic.pdf  | title=Dear UNIX enthusiasts  | accessdate=2009-12-04  | date=2002-01-23 }}</ref> under a [[BSD_licenses#UC_Berkeley_advertising_clause|4-clause BSD]]-like license, allowing its use in other open source products.