Now, take a look at the four Syntax trees below. The nodes are labeled S, NP and VP.
At first sight, only the first two a seem valid ( as in S--> NP VP )
The second two seem invalid, as in (*S --> VP NP)
This is where Projection comes in.
In the picture below, all three nodes are being projected onto the outer side of the containing Field. The result: two Forms, two one-dimensional sequences green and yellow, on the left and bottom side of the tree structure.
Now let us import a syntax structure, and focus on the two Forms left and bottom.
Surprisingly, The lexical Form is positioned as a horizontal projection!
The logical form is residing at the bottom
In the examples below, a variety of trees and forms reveal the multiple Forms (interfaces) on the private tree structure.