|mois

The |mois filter (since SPIP 1.0.3, SPIP 1.0.4, SPIP 1.0.5) displays the two-digit numeric value for the month of the date to which it is applied.
[(#DATE|mois)]

The value displayed varies from 01 through to 12.

See also the |jour (day) and |annee (year) filters.