NEW YORK -- Apple Inc. on Thursday gave software developers the guidelines it uses to determine which programs can be sold in its App Store, yet it reserved for itself broad leeway in deciding what makes the cut.

The move follows more than two years of complaints from developers about the company's secret and seemingly capricious rules, which block some programs from the store and hence Apple's popular iPhone, iPad and iPod Touch devices.

The guidelines go some way toward addressing those complaints and broadening the discussion about Apple's custodianship of the App Store.

Software developer Nate Weiner said the approval process has always been "a black hole." A minor update to his Read It Later app, which saves Web pages, was rejected by the App Store for an unusual reason -- it required user registration -- and he had a hard time getting a response from the company.

"If you submit an app, you have no idea what's going to happen," he said. "You have no idea when it's going to be approved or if it's going to be approved."

The guidelines should be a big help, especially for novice developers, he said.

The rules consist of a long checklist, specifying, for example, that "apps that rapidly drain the device's battery or generate excessive heat will be rejected." Also bound to be rejected are "apps containing 'rental' content or services that expire after a limited time."

But some of the guidelines leave much for developers to figure out.

"We will reject Apps for any content or behavior that we believe is over the line. What line, you ask? Well, as a Supreme Court justice once said, 'I'll know it when I see it'. And we think that you will also know it when you cross it," the guidelines say.

Earlier this year, Apple forced the creator of a comic-book version of James Joyce's novel "Ulysses" to alter some panels featuring nudity, echoing the censorship debate in the 1920s and 1930s, when the novel itself was banned in the U.S.

In the guidelines, Apple draws a line between broader expressions of freedom of speech and the App Store.

"We view Apps different than books or songs, which we do not curate. If you want to criticize a religion, write a book. If you want to describe sex, write a book or a song, or create a medical app," the guidelines say.

Apple also says it will block applications that don't do "something useful or provide some lasting entertainment."

Corynne McSherry, an attorney at the Electronic Frontier Foundation, a watchdog group, said the guidelines help, but Apple customers should remain concerned that Apple is dictating the content of third-party software.

"These strict guidelines are limiting what's available to Apple users," she said.

The App Store's chief competitor, Google Inc.'s Android Marketplace, has few restrictions for developers. That's been welcomed by developers, but has also led to a flood of low-quality applications and even some that prey on buyers. Security firm Kaspersky Lab said it found one media player application that secretly sends text-message payments -- which get added to phone bills.