The National Stock Exchange, which so far said there was no overcounting of subscriptions to book-built issues on account of the multiple bidding system, has quietly added a caveat on its Web site displaying the ONGC issue data.

The subscription numbers of the issue have been qualified with two asterisks and the remark at the bottom says, "The bid figures are inclusive of optional bidding quantity".

In other words, NSE, too, follows the same system of counting multiple bids and does not net them off to arrive at the final subscription figure.

An NSE executive insisted that the caveat was not a new addition. However, a search on the NSE Web site shows that the subscription figures of none of the recent public sector issues have the caveat.

On its part, BSE has decided to stick to the old methodology, though it had officially said on Friday that it was taking a close look at its existing software program and making necessary changes to net off multiple bids to get the correct subscription figure.

"There is no change in the procedure or the software used in aggregating the total bids received under the book-building process for PSUs. BSE has been consistently following the same process in regard to multiple options chosen by investors, which is the accepted practice. Changes, if any, will be made only in consultation with the Securities and Exchange Board of India," a BSE release said.