Book of Common Prayer (page 36)

Concerning the Service

In the Daily Office, the term "Officiant" is used to denote the person,
clerical or lay, who leads the Office.

It is appropriate taht others persons be assigned to read the Lessons,
and to lead other parts of the service not assigned to the officiant.
The bishop, when present, apporpriately concludes the Office with a
blessing.

At celebrations of the Holy Eucharist, the Order for Morning or Evening
Prayer may be used in place of all that precedes the Offertory.

Additional Directions are on page 141.