gl2 shader update to gl3

Hi. I'm trying to convert gl2 shader program (gm.illumlines.jxs) to gl3 version.

I have managed to add all checklists that Cycling74 suggest, but still there's an syntax error and blank lines.

what's the equivalent of gl_FrontColorIn[1] and gl_PositionIn[3] for gl3? many tutorials said gl_FrontColor can be replaced by declaring in vec4 color and binds it. I keep getting syntax error.

here's my gl3 vertex shader:

#version 330 core

out vec3 P;
out vec3 T;

in vec4 color;

void main(void)
{
    color = color[1];
    T = gl_PositionIn[2].xyz - gl_PositionIn[1].xyz;
    P = gl_PositionIn[1].xyz;
    gl_Position = projectionMat*vec4(gl_Position[1], 1.0);
    EmitVertex();

    color = color[2];
    T = gl_PositionIn[3].xyz - gl_PositionIn[2].xyz;
    P = gl_PositionIn[2].xyz;
    gl_Position = projectionMat*gl_PositionIn[2];
    EmitVertex();

    EndPrimitive();
}

and this is original part

#version 120
#extension GL_EXT_geometry_shader4 : enable

varying out vec3 P;
varying out vec3 T;

void main(void)
{
    gl_FrontColor = gl_FrontColorIn[1];
    T = gl_PositionIn[2].xyz - gl_PositionIn[1].xyz;
    P = gl_PositionIn[1].xyz;
    gl_Position = gl_ProjectionMatrix*gl_PositionIn[1];
    EmitVertex();

    gl_FrontColor = gl_FrontColorIn[2];
    T = gl_PositionIn[3].xyz - gl_PositionIn[2].xyz;
    P = gl_PositionIn[2].xyz;
    gl_Position = gl_ProjectionMatrix*gl_PositionIn[2];
    EmitVertex();

    EndPrimitive();
}