493bbc30__Touch_Gesture_Reference_Guide__Platform_Description
[Platform] Microsoft Windows 7 [Platform Gesture] Two-Finger Tap [Core Gesture] Tap (Two-finger) [Platform Description] 
Tapping with two fingers simultaneously zooms in about the center of the gesture or restores to the default zoom – great for zooming in on hyperlinks.
LukeW | Touch Gesture Reference Guide
Platform Description