Blue Book 7 B 1 - Clarification
In reviewing Partnership Understandings: Level 4 --- 7B1 (iii) Any meaning showing at least four cards in a specified suit, forcing or not.
Perhaps I have missed something, but the number of cards should be three (same as Level 2 better minor scenario).
Comments
I think that comes under 7B1(c)
"Any distribution that satisfies the requirements for a natural 1NT opening."
Since the statement about opening on 3-card suits is
"... including the possibility of a three-card minor suit opening on some balanced hands. 6C3
What you are missing is the other three options included under 7B1. Three card minors (or indeed doubletons) are included in 7B1(i)c:
(i) Forcing or not, showing any combination of the following hand types:
c) Any distribution that satisfies the requirements for a natural 1NT opening (see 7B3(i)
below) subject to the minimum strength requirement of 7A3 for suit openings.
The bit you quoted would allow you to play 1C as showing 4+ hearts, for example.