Spanish to English Tech/Engineering Automotive / Cars & Trucks paintwork repair/bodywork

"• "S": Magnitud de la superficie a pintar (m2). Su valor debe identificarse con la superficie exterior que va a recibir las pinturas de acabado. Por tanto, "S" puede coincidir con la magnitud de la pieza completa o puede tomar el valor de una zona parcial de la pieza (pintado de zonas con *cambio de perfiles*, etc.). "

What this is referring to is where a bodywork part may have a "crease" or an angle in it. If you're repainting, you may not have to repaint the whole part, but only up to the "crease". Hope this makes sense. I don't think I've ever had to translate this before and I'm stumped. It may be oh so obvious, but it's been a loooong week, so many thanks to you all in advance!