After the release of MPI-2.0, the MPI Forum kept working on errata and clarifications for both standard documents ( MPI-1.1 and MPI-2.0). The short document ``Errata for MPI-1.1'' was released October 12, 1998. On July 5, 2001, a first ballot of errata and clarifications for MPI-2.0 was released, and a second ballot was voted on May 22, 2002. Both votes were done electronically. Both ballots were combined into one document: ``Errata for MPI-2,'' May 15, 2002. This errata process was then interrupted, but the Forum and its e-mail reflectors kept working on new requests for clarification.
Restarting regular work of the MPI Forum was initiated in three meetings, at EuroPVM/MPI'06 in Bonn, at EuroPVM/MPI'07 in Paris, and at SC'07 in Reno. In December 2007, a steering committee started the organization of new MPI Forum meetings at regular 8-weeks intervals. At the January 14--16, 2008 meeting in Chicago, the MPI Forum decided to combine the existing and future MPI documents to one document for each version of the MPI standard. For technical and historical reasons, this series was started with MPI-1.3. Additional Ballots 3 and 4 solved old questions from the errata list started in 1995 up to new questions from the last years. After all documents ( MPI-1.1, MPI-2, Errata for MPI-1.1 (Oct. 12, 1998), and MPI-2.1 Ballots 1--4) were combined into one draft document, for each chapter, a chapter author and review team were defined. They cleaned up the document to achieve a consistent MPI-2.1 document. The final MPI-2.1 standard document was finished in June 2008, and finally released with a second vote in September 2008 in the meeting at Dublin, just before EuroPVM/MPI'08.