Microsoft's touch language for Windows 8 PCs requires digitizers that support a minimum of 5 fingers.
As Microsoft execs Jeff Piira and Jerry Koh explain, developers did not want their creativity to be limited to two fingers like in Windows 7 - and will now be able to include whichever multi-finger gestures or controls are useful for a particular application.
"We focused on a minimum of 5 fingers to enable scenarios like whole hand interactions (all 5 fingers) or multi-finger/multi-hand scenarios," Piira and Koh explained in a Building Windows 8 blog post.
"This will address the feedback, and unlocks opportunities for developers to push the envelope with multi-touch applications. So a new Windows 8 PC is going to be much more consistent and predictable both from a user and developer perspective."
The two also confirmed that new UI concepts in Windows 8 Metro will impact touch hardware design. For example, the edge swipe required to reveal the charms and app bars fundamentally changes all the assumptions made on touch hardware.
"Traditionally, the edges of the screen are where touch sensitivity drops off, and it's a place that hardware manufacturers have traditionally not placed much emphasis on. The center of the screen received all the innovation, while the edges have suffered.
"[However], the edge swipe is a critical part of using Windows [and] has a big role to play in our developer promise - as every pixel used to detect an edge swipe is a pixel taken away from the developer. For Metro style apps, where every pixel belongs to the dev, it is critical that we uphold and deliver on this promise," they added.