Zelda producer Eiji Aonuma has revealed that a master timeline for the series does exist. How so? He's told ONM that Skyward Princess takes place before The Ocarina of Time.
But speaking to the mag, he wouldn't go into more specifics about the timeline, saying it was "confidential."
"Yes there is a master timeline but its confidential document," said Aonuma. "The only people to have access to that document are myself, Mr. Miyamoto and the director of the title. We cant share it with anyone else!"
But Aonuma then dropped the Skyward Sword/OoT connection.
"I have already talked to Mr. Miyamoto about this so I am comfortable in releasing this information – this title [Skyward Sword] takes place before Ocarina of Time."
He went on to further explain the timeline a bit more.
"If I said that a certain title was ‘the first Zelda game’, then that means that we cant ever make a title that takes place before that," he said.
"So for us to add titles to the series, we have to have a way of putting the titles before or after each other."
The Legend of Zelda releases next year for Wii.