title: Documentation or specification for .step and .stp files
body: <p>I am looking for some kind of specification, documentation, explanation, etc. for .stp/.step files.
  It's more about what information each line contains instead of a general information.</p>
  
  <p>I can't seem to figure out what each value means all by myself.
  Does anyone know some good readings about STEP files?</p>
  
  <p>I already searched google but all I got were information about the general structure instead of each particular value.</p>