Vyaptescha samanjasam III.3.9 (368)

And because (OM) extends (over the whole of the Vedas), (to specialise it by the term 'Udgitha') is appropriate.

Vyapteh: because (OM) extends (over the whole of the Vedas); Cha: and; Samanjasam: is appropriate, consistent, justifiable.

Sutra 7 is elaborated here.

In the Sruti 'Omityetadaksharamudgithamupasita', the use of the word Udgitha as Viseshana, i.e., adjective of OM is appropriate, because OM by itself is pervasive in all Srutis and should not be understood here in its general sense.

In the passage "Let a man meditate on the syllable OM as the Udgitha", the two words 'Omkara' and 'Udgitha', are placed in coordination. The question then arises whether the relation in which the ideas conveyed by these two words stand to each other is the relation of superimposition (Adhyasa) or sublation (Apavada) or unity (Ekatva) or specification (Viseshana).

The word 'and' stands here in place of 'but' and is meant to discard the three other alternatives. The fourth is to be adopted. The fourth and correct view is that the one is Viseshana (an adjective) to the other as in the words Nila-Utpala (blue lotus). The passage means that Udgitha is the Viseshana of Omkara. The appropriate view of the Chhandogya passage is to take the word Udgitha as specialising the term 'Omkara'.