China is becoming increasingly important to Apple's bottom line

During Apple's earnings call today, Apple SVP and CFO Peter Oppenheimer announced a small change to how the company reports its revenue from Asia. Rather than lumping China into the "Asia Pacific" category as has been done up to this point, a new "Greater China" category has been added.

"Beginning this fiscal year, we are reorganizing the presentation of our results to provide greater transparency," Oppenheimer explains. "First, we have established a new operating segment of Greater China given the very significant contribution of that region to our overall business. We define Greater China to include Mainland China, Hong Kong, and Taiwan."

While the edit to the company's revenue data sheet may be minor, it's a sign of something much larger: China's smartphone market could become Apple's most important battleground. Apple's year-over-year iPhones sales in China more than doubled last quarter, with revenue jumping an astonishing 67%. This puts China in third place in terms of contributing to the company's overall bottom line, but China's smartphone war is just heating up.

Last year, China surpassed the United States to become the largest smartphone market in the world. This year, the Chinese market could grow to be twice that of the U.S., so it's relatively easy to see why Apple would want to focus on the region.

Apple has already had a great deal of success with the iPad mini in China, and the company even went so far as to publish a Chinese New Year gift guide. But those are just small steps towards declaring victory, and Apple's actions in 2013 will be infinitely important to whether China remains a revenue boon for the company.