My old posts make the same error, if I recall correctly axxel57 is the one that first mentioned the difference a few years back.So, now I have to go back and correct all my numerous old posts - I'm not sure I have a single 156 (quite certain I don't ) but do I have a boatload of 109 and 150/152 (109 upgraded) stages... Not a single one was obtained as a balanced adjustable.
The situation reminds me of a time when the term R109/R156 was somewhat common. I credit Couv for helping educate me to the fact that there is no such thing as a R109, it's simply a 109.