Baron is reached only by the sequence:
1X - 2NT
With NO opponent intervention
It shows 16+HCP and a balanced hand - NO 5 card suits
It invites the partnership, starting with the opener to bid 4 card suits 'up the line'
Taking the suits from Clubs upwards a four card suit is bid and in the
case of Opener he may rebid his opening suit if it is 5 cards.
Responder may show a four card suit or 3 card support for opener's suit.
1H - 2NT - 3NT - PASS : shows opener's distribution to be 3433 precisely
1S - 2NT - 3D - 3H - 3NT... Shows opener's distribution as 5-4
Hearts and Diamonds & responder has shown 4 card Heart support.
If responder continues with 4NT: this is Quantitative.