Correct, and similar tolerances apply to the metric equivalents in B18.2.4 (although they do not specify the wrench).
Either way, for an adapter that's going to be used with a stock lug wrench the ¾" is a negligible variance.

 

The metric wrench opening tolerances are given in International Standard ISO 691. Yes, the differences between metric and inch-fractional sockets seem small, but they are real and significant when compared to the thickness (thinness) of the stainless steel caps on the original Jaguar lug nuts. Only a little extra play in the socket can contribute to deformation or spinning of the cap.

We have decades of reports of owners damaging their stainless steel-capped Jaguar lugs by using incorrect sockets. So it's important that the information we share in the forums be consistent with Jaguar's specifications rather than the "close enough" claims of aftermarket lug nut sellers.

You obviously know how to judge the fit of your sockets on your lug nuts, but not every owner does, so it's best that we share the most accurate information.

Cheers,

Don