25. The maniple is no longer required.
26. The celebrant may wear the chasuble for the Asperges before Mass on Sundays, for the blessing and imposition of ashes on Ash Wednesday, and for the absolution over a coffin or grave.
27. A concelebrant must wear the vestments obligatory for individual celebration of Mass (Rite of Concelebration no. 12).
When there is a serious reason, for example, a large number of concelebrants and a lack of vestments, the concelebrants, with the principal celebrant always excepted, may leave off a chasuble but never the alb and stole.