Blueprinting... Educate the uneducated

Your definition is correct, think about it. Those paper blueprints contain all of the measurements/specifications of the part to be constructed/built. Where the doors and windows will be placed, the distance between them, how big they should be. Blueprinting an engine has reduced that paper to just the specifications. Now you have to understand machining as opposed to construction. How an engine is machined from a raw casting at the factory, all the different machining operations you need to understand what makes up the engine sitting in front of you. Blueprinting an engine then refers to revisiting/double checking all or most of these machining operations to bring the engine back to specifications. To describe each machining operation would take more space than we have here. Now you can research individual operations. Hope this helps.