While reading Raja Yoga by Swami Vivekananda, I found that he is talking about commentator.
On the 27th Sutra:
तस्य वाचकः प्रणवः ॥२७॥
27. His manifesting word is Om.
. . . . . Our commentator says, "Although the relation between thought and word is perfectly natural, yet it does not mean a rigid connection between one sound and one idea." These sounds vary, yet the relation between the sounds and the thoughts is a natural one. The connection between thoughts and sounds is good only if there be a real connection between the thing signified and the symbol; until then that symbol will never come into general use. A symbol is the manifester of the thing signified, and if the thing signified has already an existence, and if, by experience, we know that the symbol has expressed that thing many times, then we are sure that there is a real relation between them. Even if the things are not present, there will be thousands who will know them by their symbols. There must be a natural connection between the symbol and the thing signified; then, when that symbol is pronounced, it recalls the thing signified. The commentator says the manifesting word of God is Om. . . . .
I know about two commentators Vyasa and Vijnanabhikshu.
So, who is the commentator of YogaSutras Swami Vivekananda is talking about in his work Raja Yoga?