Nicene and Post-Nicene Fathers, Ser. II, Vol. XIV:
The Canons of the Synods of Sardica, Carthage, Constantinople, and Carthage Under St. Cyprian, Which Canons Were Received by the Council in Trullo and Ratified by II. Nice.: Canon XCV

Canon XCV.  (Greek xcviii.)

An universal council to be held only when necessary.

It seemed good that there should be no more the yearly necessity of fatiguing the brethren; but as often as common cause, that is of the whole of Africa, demands, that letters shall be given on every side to that see in this matter, that a synod should be gathered in that province, where the desirability of it induces; but let the causes which are not of general interest be judged in their own provinces.

p. 491 Notes.

Ancient Epitome of Canon XCV.

When general necessity so urges, letters are to be sent to the chief see, and a synod held in a convenient place.  But let ordinary causes be settled in their own provinces.

This canon is Canon j. of the Synod of Carthage, a.d. 407.

Johnson.

This canon is a tacit revocation of that clause for annual synods in the 18th canon, which was made in a former council.