By PETER M. NICHOLS

In content and promotional impact, “The Lord of the Rings” trilogy is a multifaceted machine. Last August “The Fellowship of the Ring,” the first of Peter Jackson’s three films, was released on DVD with a fair-size list of extras. In November a much-extended special edition appeared with 30 more minutes woven into a movie that already ran 178 minutes, and with many more extras to examine every aspect.

Increased length is usually a mistake. In this case it was a triumph: “Fellowship” was the consensus DVD of the year. That success, of course, did no harm to “The Lord of the Rings: The Two Towers,” the second part of the trilogy, which opened in theaters in December and eventually earned $339 million at the box office.

This week New Line began the routine all over again with a “Two Towers” DVD (and in deference to the 50 percent of households without a DVD player, videocassette). An enlarged special edition, with more than 40 minutes added into the movie, is scheduled for November release. On Dec. 17, the third film, “The Lord of the Rings: The Return of the King,” is to open in theaters.

“One of the key differences this year is the amount of awareness,” said Matt LaSorsa, senior vice president for marketing at New Line Home Entertainment. That attests to the growing influence of DVD, in this case Mr. Jackson’s all-enveloping use of it as a part of the movie-making and promotional process.

But why buy a “Towers” DVD now when a bigger one is coming along in less than 90 days (albeit at a $39.99 suggested retail price versus $29.95 for the first version)? The answer depends on how much DVD you’re looking for; the two releases are intended for two audiences, and features don’t repeat themselves.

The current DVD has the 179-minute movie that played in theaters. “It’s for people who don’t like to sit through an even longer film,” Mr. Lasorsa said. Behind-the-scenes documentaries probably tell moderate fans all they want to know about the making of “The Two Towers.” For those interested, these features also describe the making of the much more elaborate November DVD edition and offer a preliminary look at the making of “The Return of the King.”

For rabid fans the November disc will have the 215-minute extended version and added material describing it and the trilogy as a whole.

The three movies were shot in New Zealand during an 18-month period beginning in 2000. From then on “Rings” movie-making and DVD production have proceeded at the same time on an integrated production line.

On the discs, actors taken back to New Zealand reshoot scenes for “The Return” and do interviews and commentary for both “Towers” DVD’s. Mr. Jackson moves from editing the third movie to working on the DVD’s of the second and back again.

Much of the reshooting for “Return” and the expanded “Towers” is to heighten the personalrelationships in films heavy on battle. Like many other directors, Mr. Jackson says one of the pleasures of DVD is being able to reassure actors that scenes cut to shorten theater running times can be put back on disc.