From SMTheming Wiki
linear command animates an element directly from one state to the next over a specified period of time. No acceleration or deceleration is used to "smooth" the beginning or end of the animation.
The time parameter is the number of seconds that it should take to go from the current state to the next state.
To make an element slide abruptly 80 pixels to the right:
To have an element "flip" downwards on the screen: