A mise en pratique for the definition of a unit is a set of instructions that allows the definition to be realized in practice at the highest level. The mise en pratique should describe the primary realizations based on top-level primary methods (see the report of the 97th meeting of the CIPM (2008)).
Mises en pratique for the existing definitions are published online in Appendix 2 of the SI brochure. They are updated as required, following the advice of the relevant Consultative Committees.
The CCEM has already prepared a draft mise en pratique for the ampere and other electric units, and the CCM and CCT are working on the draft mises en pratique for the kilogram and kelvin, but of course such documents can not be finalized until the redefinitions are decided.
The BIPM is developing an ensemble of reference mass standards which will play an important role in the mise en pratique of the future definition of the kilogram.