Page 46 of the 2016 F1 sporting regulations:
So, if I've understood correctly, the manufacturers have to send a complete dossier of the 2016 power units... tomorrow. This means Honda will not run different PUs during test session I think.Any manufacturer intending to homologate a new power unit during the 2016-2020 period
must provide the FIA with full details of the power unit on or before 28 February of the year of
homologation. The FIA must be satisfied, at its absolute discretion, that such a power unit
could fairly and equitably be allowed to compete with other homologated power units.
Details of the above power unit must be included in a dossier supplied to the FIA 14 days prior
to the date of homologation. The manufacturer must hold a complete power unit to this
specification in a container sealed by the FIA prior to the 28 February of the year of
homologation.