Complex sentence: The above description describes either the so-called "slow denies" variant, where strong hands must bid 2NT first to deny a stopper, or the "slow shows" variant, direct bid of level 3 denies a stopper and 2NT promises it.
Split into simpler sentences: The above description describes so-called "slow denies" variant, where strong hands must bid 2NT first to deny a stopper. In the "slow shows" variant, direct bid of level 3 denies a stopper and 2NT promises it.