The Financial Times is not backing down from its high-profile fight with Apple, even after the software maker relaxed its controversial subscription policy.

On Tuesday, the FT announced its iPad app was “moving” to the open web. The HTML5-powered, download-free web app is every bit as functional as the native app, but the FT gets to maintain total control over subscription pricing and subscriber data — at the cost of the promotional platform of Apple’s App Store.

Under Apple’s new set of rules, it will no longer require pricing parity — that is, the old rule that a subscription in the App Store must cost the same (or less) than it does everywhere else. Apple will also allow publishers to sell subscriptions only outside of the store, eliminating the requirement that they must be sold through Apple as well.

But there’s still one problem that will keep the FT from embracing Apple’s new system, Rule 11.13:

11.13 Apps that link to external mechanisms for purchases or subscriptions to be used in the app, such as a “buy” button that goes to a web site to purchase a digital book, will be rejected

In other words, apps are prohibited from linking to outside subscription sites. The FT could advertise subscriptions on its website and then direct users to the app — but not the other way around. The FT considers that unacceptable and said the app that would result would be a “dumb app.”

“The fact remains that the publication still wouldn’t be able to sell subscriptions within an app using our own system, so all we’d be allowed to do is offer an app — that’s what they called dumb — for subscribers who purchase it somewhere else,” said Tom Glover, a Financial Times spokesman.

That restriction could impact other news apps as well. The current version of the New York Times iPad app, for example, employs its own subscription system. Tap “Subscribe Now” and an NYT webpage pops up. That would not seem to be allowed under Apple’s new rules. As Josh explained earlier, the ease and ubiquity of one-tap purchasing, tied to 225 million credit cards, is a powerful incentive to play by Apple’s rules.

The FT, with a loyal niche audience, appears willing to go its own way. What remains to be seen is whether Apple would pull the FT’s existing iPad app from its store or refuse to approve future app updates. The FT has said there are “no plans to pull out of any apps store,” and an update pushed out yesterday suggests the app is still being developed.

Update: I received further comment from Rob Grimshaw, the FT’s managing editor, who sent this statement:

The FT Web App will continue to be our main focus. We will be adding new features to the web app first and any native app development will be considered on its merits on a case by case basis. We will be giving consideration to Apple’s terms within this context. While it’s certainly positive that they have made concessions, the FT still wouldn’t be able sell subscriptions within a native app using our own payment system.