As orignally referred to by Jung - and correctly understood - the so-called 'tertiary' function is also an 'auxiliary' function but I accept that in MBTI-related publications that only the first auxiliary is referred to as such.  In Jung's 'Psychological Types' both are referred to as 'auxiliary' functions so it is not out of place in this article to clarify this difference in how the term is used.             

My concern about using "auxiliary" to describe the tertiary function has nothing to do with its correctness with respect to Jung's writing. In the context of this article, I believe it does more to create confusion than to add value. So for the sake of the reader, I believe it's better left out. And at any rate, this article isn't about Jung, except in terms of his influence on Katharine Briggs and Isabel Myers.