Geometry shaders are core 3.2. But it isn’t implemented the way EXT_geometry_shader4 is. The special input variables for geometry shaders are defined in an input layout block called “gl_in”, which is an array. See the GLSL 1.5 specification for more details.
Indeed! (Just recently did read the 1.5 spec from cover-to-cover and looking at the notes of that undertaking - i have noticed that difference and marked it with “???” … just kind of forgot that. x_x)