Why did GLSL change by an inch?

Question

I know how to use in / out variables and variables. I fully understand that using in / out variables is better because it does not depreciate.

It is very small, but I do not understand why they changed it. Previously, I could have the code in one shader, copy and paste it into another, and everything will be fine. Now I have to paste it into another and change everything to "out" (instead of "in").

I am not against this, I am very curious if there is an advantage for the in / out variables, and if not, why the Khronos group changed it.

Answer 1

, . OpenGL 3.2 Geometry Shaders, Vertex Fragment. VS FS.

... , ? VS FS GS. - , VS FS. , , - , .

GS. . , VS varying GS; .

, /, . in/out; .