The Securities Industry Association hasn’t decided whether it supports the New York Stock Exchange’s plans to ramp up its use of trading automation.

While the SIA says that it supports efforts by the NYSE to enhance its direct trading facility, which will provide more execution choices to investors, it notes in a comment letter that the proposal is “incomplete” and lacks “important details and concrete examples of how the system will operate.”

In a comment letter to the Securities and Exchange Commission sent Friday, Donald Kittell, SIA executive vp, wrote the hybrid market proposal “is difficult to evaluate … without more information.”

Only after additional information has been provided, the letter said, can SIA evaluate the proposal to see if it “contributes to fair and orderly markets, fosters competition among markets, and protects investors.” Until then, it says it can’t support or oppose the proposal.