Canon I.
The Fourth Ecumenical Council (Chalcedon, 451) · The Seven Holy Ecumenical Councils
We have judged it right that the canons of the Holy Fathers made in every synod even until now, should remain in force.
Chal 16.1.3
Before the holding of the Council of Chalcedon, in the Greek Church, the canons of several synods, which were held previously, were gathered into one collection and provided with continuous numbers, and such a collection of canons, as we have seen, lay before the Synod of Chalcedon. As, however, most of the synods whose canons were received into the collection, e.g. those of Neocæsarea, Ancyra, Gangra, Antioch, were certainly not Ecumenical Councils, and were even to some extent of doubtful authority, such as the Antiochene Synod of 341, the confirmation of the Ecumenical Synod was now given to them, in order to raise them to the position of universally and unconditionally valid ecclesiastical rules. It is admirably remarked by the Emperor Justinian, in his 131st Novel, cap. j.; “We honour the doctrinal decrees of the first four Councils as we do Holy Scripture, but the canons given or approved by them as we do the laws.”
Chal 16.1.8
It seems quite impossible to determine just what councils are included in this list, the Council in Trullo has entirely removed this ambiguity in its second canon.
Chal 16.1.9