Using a 2/1 GF system, what does a reverse by the opener after a 2/1 GF bid mean? E.g. 1H, 2D, 2S, or 1S, 2H, 3C. After consulting different volumes on 2/1 GF systems I seem to have found three very different approaches: (a) the reverse shows no extra values, (b) the reverse shows extra values as in a non 2/1 GF system, or © the reverse shows no extra values at the two level, but does show extra values if made at the three level. Which do you use/prefer and why? Thanks in advance.