Class B airspace notation

Airbus writes:

It is specifically indicated on the chart, in every case.

Point me to an example.

Class E is usually implied rather than explicit. Although it nominally starts
at 14,500 feet MSL, so much of the U.S. is an exception to this that the
absence of any marking implies an exceptional floor of 1200 feet AGL. Only
Class E that starts at 700 feet, or starts at the surface, or that starts at
1200 feet _and_ is adjacent to Class G, or that starts at some other altitude
besides 14,500, is explicitly delimited. So if you see [27] for a Class D
airspace and 50/28 for the Class C above it, between 2701 feet and 2799 feet,
it's Class E. If you see [27] for the Class D and 50/27+ for the Class C,
it's Class D up to 2700 feet inclusive, and Class C from 2701 feet up to 5000
feet inclusive, and Class E and A above, in that order.

The above proves the contrary.

It doesn't prove anything, since you've given no examples.