title: What is a SubProgram ".........." in Unity shader?
body: <p>The practical part of the code is doing What?</p>
  
  <pre><code>//this partical &gt;&gt;   SubProgram "opengl " {    &lt;&lt;&lt;
  Keywords { "LIGHTMAP_ON" "DIRLIGHTMAP_ON" "HDR_LIGHT_PREPASS_OFF" }
  Vector 0 [_Color]
  SetTexture 0 [_MainTex] 2D 0
  SetTexture 1 [_LightBuffer] 2D 1
  SetTexture 2 [unity_Lightmap] 2D 2
  "!!ARBfp1.0
  PARAM c[2] = { program.local[0],
          { 8 } };
  </code></pre>