Indeed Duncan. :-)
his rule could be replaced by the strong juxtaposition
"strong juxtaposition" already existed even then in Terms (which Lennes called Terms/Products, but somehow missed the implication of that) and The Distributive Law, so his rule was never adopted because it was never needed - it was just Lennes #LoudlyNotUnderstandingThings (like Terms, which by his own admission was in all the textbooks). 1917 (ii) - Lennes' letter (Terms and operators)
In other words...
Funny enough all the examples that N.J. Lennes list in his letter use
...Terms/Products., as we do today in modern high school Maths textbooks (but we just use Terms in this context, not Products).