The New York Stock Exchange has filed another amendment to its plans to expand electronic trading with the Securities and Exchange Commission.

The NYSE first proposed to expand its NYSE Direct+ service back in February 2004. It submitted a supplemental filing in August. Now, it has added another supplemental filing that further clarifies the rules and functionality of the expanded automatic order-execution service.

The supplemental filing details the rules governing automatic-execution orders, sweeps of the limit-order book, specialist and broker interest files and algorithms, and other features of the hybrid market such as “liquidity replenishment points” – the points at which the auction will have an opportunity to supply liquidity to dampen volatility. Also included are multiple specific examples on how orders will be handled under various trading scenarios.

“Blending the auction market with more automation reflects the exchange’s commitment to our customers and further developing our market,” said NYSE CEO John Thain. “The hybrid market provides the most compelling array of choices for trading NYSE-listed securities and will allow us to better accommodate the diverse trading strategies of our customers.”

In the hybrid market, floor brokers will be able to electronically represent large customer buy and sell orders at the point-of-sale. To assist specialists with market making responsibilities and to maintain fair and orderly markets, proprietary software will allow specialists to automatically supplement liquidity in a fast market environment, the NYSE notes.

The NYSE’s latest rule filing and related information are available at www.nyse.com/direct.