Ardent fans of PeterGreenaway must have been left scratching their heads in puzzlement last week afterthe Venice Film Festival announced that Episode 3 (Antwerp) would have its world premiere on the Lido as thenext instalment of his on-going Tulse Luper Suitcases project.

After all, it hasonly been a matter of months since the first part in this supposed Tulse trilogy premiered at the Cannes FilmFestival (under the title Part 1: The Moab Story).

Had the Venetianprojectionist got the reels muddled up or is it a case of Greenaway beingunable to count'

It turns out thatthe reasons that Episode 3 is screening in Venice - without anyone having seen No 2 - are rather morecomplicated than a simple case of bad arithmetic or Italian mishandling. Indeedthere is a very real possibility that Greenaway, who is both eminently numerateand literate, may be in the midst of making a four-part "trilogy".

Marketing andselling multi-part features - as Lord Of The Rings (should that be one Oscar run or three')and Kill Bill (oneminimum guarantee or two', the American version or the special Asian edition')have both recently underlined - is clearly an inexact art that is still being refined.

Antwerp, Greenaway's two-hour piece that willscreen at a special out-of-competition event attached to the Upstream (ControCorrente) section of Venice, is neither the second film of the Tulse Luper trilogy, nor is it an unfinishedwork-in-progress.

Key tounderstanding the difference is something that sounds like semantics, but inGreenaway's case is not.

He has writtenthe Tulse Luper storyin 16 "episodes" of different lengths. (Each has a name as well as a number.)These are being combined and released in the form of three feature films,called "parts", the first of which showed in competition in Cannes. The whole projectis accompanied by a series of DVDs and a labyrinthine (and still growing)website.

What Venice is toshow is an episode, a separate story whose first 40 minutes have already beenseen as part of the Cannes film, but whose final 80 minutes comprises of previouslyunseen material some of which may be used in the second feature, Part 2: From Vaux To The Sea.

"The episode Antwerp had once been conceived as a film on itsown, but eventually grew into Tulse Luper Suitcases," says Allard van der Werff, who is bothassistant to Greenaway and on the staff of producer Kasander Films.

Industryobservers used to reading between the lines of press statements and festivalline-ups may draw their own conclusions as to why Greenaway would choose topresent something other than the fully-formed second feature. But none of TulseLuper's many producers,its sales agent Fortissimo or other spokespeople would be drawn on the precisestate of readiness of Part 2.

The TulseLuper portmanteau isarguably Greenaway's masterwork and may be the key to understanding the UK director'sentire film oeuvre. While he has shot entirely new material for it (andcontinues to shoot more), Greenaway's ambitious take on the history of the 20thCentury, also delivers a narrative that knits together themes, references andeven text taken from his earlier features, and shorts such as Water Wrackets. Tulse Luper was simply never going to bestraightforward to deliver.

One earlierversion of the trilogy's release and marketing strategy had the first featureappearing at Cannes, the second at Venice and the final part (Part 3: From Sark To Finish) projecting in Berlin. A current versionsuggests that Berlin and a return to Cannes could now be on the agenda(assuming of course that those festivals' selectors are prepared to play ball).

Van der Werffsays it is unclear at what occasion Part 2 will emerge, but says that a multi-mediaextravaganza is being planned around Tulse Luper for next February's Berlinale. "We are planning a'circus tour' of the episodes. Berlin could possibly be an episode event, as wewill also be launching the game around that time and DVDs," he said.

Van der Werff isvery upbeat about the Venice outing for Antwerp. "We will be showing it as it was intended, using adigital, high definition projection system. It allows Peter to put things outthere more vigorously," says van der Werff. "Other festivals can be hesitantabout HD screenings in their competition, seeing them as unfinished or needinga transfer to 35mm. HD in its many versions, is actually much more complex thanthat and Venice is making the effort."

Whether all thedifferent versions - a digital version of Part 1 shown at last month-s Cambridge festival was said tobe different to the 35mm Part 1 shown at Cannes - will end up baffling Tulse Luper's potential audience is moot.

"We've alreadyseen from the Greenaway and Tulse Luper fan-sites on the web that people there get thedistinction between 'parts' and 'episodes'", says van den Werff. Butrecognising that non-Greenaway cognoscenti may need some help, van den Werffadds sheepishly: "we do need to inform better about this, and we are going to."

However, there isstill room for more expansion of the mind, if Greenaway chooses to go into StarWars-mode and deliverprequels. "I've seen a total of 24 episodes, eight of which will not be part ofthe trilogy," says van der Werff. "He could even add other episodes that startbefore."

But if that isconfusing, one thing at last has been settled. Tartan Films, the independentwhich until recently was called Metro Tartan Distribution and for the last twoyears has been going from strength to strength, is to be the trilogy's distributorin Greenaway's home territory, the UK.

The film hadpreviously been on the slate of Rupert Preston, the distributor who leftMetrodome two years ago and set up a distribution division for Matrix FilmFinance, Tulse Luper'sBritish tax financier.

In a statementlast week Tartan confirmed that it would be taking Part 1 to this month's Edinburgh festival.However, at the time of going to press, neither Tartan nor Kasander Films,which is the UK co-producer, were willing to comment in any more detail on thedistributor switch.