University of Colorado
The CMIP6 experimental design and organization has been agreed at the WGCM 18th Session in October 2014, see details on the CMIP Panel website at http://www.wcrp-climate.org/index.php/wgcm-cmip/about-cmip. Part of this covers the creation and timeline of the CMIP6 Data Request.
The data request is available through a repository, and the latest version is available here (updated March 10th, 2017):
An overview of the pressure levels proposed for atmospheric diagnostics is available for discussion (here).
Key documents describing the request (in the "docs" directory of the repository) are:
Guidance on information request issued in December 2014 (updated, Jan. 16, 2015): CMIP6 Data Request Compilation Guidance Note
Data Request: A request from the CMIP panels to the modelling groups for data to be contributed to the archive, specifying the variables which are needed for each experiments.
Data Requirements: Documents specifying how the data should be delivered to the archive
MIP tables: tables which define the variables included in the data request. The "Data Request" and "Data Requirements" overlap, and the MIP tables are part of this intersection.