Graeme Smith has joined the growing debate over the 2.5m clause in the UDRS by saying he was aware of the rule and understood it. Smith has not yet had to deal with the practical implications of the clause, although there were two instances in the match between South Africa and Netherlands in Mohali where it could have come into play.

Bas Zuiderent was given out lbw to Robin Peterson in the 22nd over of Netherlands' innings. Zuiderent was struck low on the front foot and was given his marching orders by Asoka da Silva. He did not review the decision but replays showed the impact was 2.5 meters from the stumps. The second incident was when Imran Tahir dismissed Berend Westdijk, who was the last wicket to fall. The on-field umpire ruled that Westdijk was out but the batsman called for a review. Replays showed that the point of impact on Westdijk's pad was 2.5 metres from the stumps as well.

Zuiderent's decision was not reviewed and Westdijk's decision was not changed because the on-field umpire had initially ruled that he was out.

According to the ICC's manual for the review system, if an "out" decision is reviewed, in order to prove that "the ball is missing the stumps, the evidence of the technology should show that no part of the ball would have made contact with any part of the stumps or bails." In the South Africa v Netherlands match, the 2.5m rule would have helped both batsmen had they been ruled not out and the fielding side had reviewed the decision, as was the case with Ian Bell against India.

While it sounds tricky, Smith said that had he been faced with the incident, he would have known what to do. "I am fine with it because it was communicated to us. I understood the rule so whether you agree or disagree with it, that's the way we were told it was going to be in this tournament. It's pretty simple I guess, you know what to expect."

Smith spoke with the kind of confidence in the law that his Indian counterpart does not have. MS Dhoni criticised the rule, calling it an "adulteration" of technology with human judgement, after the Ian Bell incident. Dhoni and India have never been in favour of the UDRS system and only used it in one Test series, its inaugural one against Sri Lanka in 2008, rejecting it for all others, before being forced to use it at this World Cup.

The ICC, through general manager Dave Richardson, had asked for Dhoni to read through the rules, as Smith claims he has done. The BCCI reacted in a strongly worded letter to the ICC, accusing them of putting unnecessary pressure on the Indian team.

The 2.5m rule exists because that is the distance that experts have identified at which the accuracy of Hawkeye begins to falter, leaving room for the on-field umpire's discretion to be used.

Firdose Moonda is ESPNcricinfo's South Africa correspondent