Starting from this SO protected question I'm trying to understand what the difference between those documents:
As you can see those documents have very different prices and I don't know if the cheaper one is valid or is something like draft or cut copy of the real standard.
Did someone buy the INCITS one?
As @Chqrlie pointed out: What is the difference between the ANSI and ISO official documents available for a free and the final draft freely accessible from the official website at open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf
I finally got answers from:
The ISO/IEC 9899:2011 is the original ISO standard published by ISO.
The INCITS/ISO/IEC 9899-2012 is the domestic U.S. adoption of the ISO.
Technically, the two standards are identical. The US version has additional front matter to add a U.S. cover and adoption date details. Once we adopt the international standard, we can set the price based on our fee schedule, which generally results in a lesser fee than buying the ISO version.
To provide more background on this, most INCITS technical committees hold U. S. Technical Advisory Group (TAG) relationships to ISO/IEC JTC 1 subcommittees and working groups and, to some ISO technical committees, subcommittees and working groups.
Subject to a few exceptions, INCITS adopts all ISO/IEC or ISO standards that fall within its program of work as “Identical” American National Standards in accordance with the ANSI “Expedited Procedures for the Identical Adoption of an ISO or IEC standard as an American National Standard”.
Similarly, INCITS will generally withdraw any such adopted American National Standard that has been withdrawn as an ISO/IEC or ISO International Standard.