Notes on responding to an overcall

From "Better Bidding with Bergen" Vol 2

In the sample auction 1C-1H-pass, responder's bids have the following meaning:

• 1S,1NT,2D Nonforcing, could be reasonable hands. The suit bids show good suits, particularly 2D.
• 2C Limit raise or better; 3+ trump and 10+ support points.
• 2H Normal single raise, usually 3 trump.
• 2S,2NT,3D Strongly invitational. The suit bids show good 6+ cards.
• 3C Mixed raise. Some offense and some defense, 4+ trumps, about 6-7 HCP
• 3H weak jump raise. 4+ trumps and nothing else, <6 points.
• 3S,4C,4D Splinter raise; rare.
• 3NT also rare; tends to deny a fit.
• 4H preemptive, but possibly better than a jump to 4H opposite a 1H opener.

If 3rd hand bids in this auction (say 1S), the schedule shown here remains mostly unchanged. A double would be responsive in principle, showing the unbid suit and tolerance (doubleton+) for overcaller's suit.