Wiki Open vs minimally invasive

[TheStephCode]

I'm looking for sound definition of an open vs minimally invasive procedure. I know certain types of surgery such as the laparoscope and robotic devices indicate minimally invasive, but in the absence of modern devices,... say, the surgeon just uses a scalpel to access, for instance,.... how is open vs minimally invasive defined?

• Size of incision?
  
• Size and depth?
  
• Visualization?

When I read an op report, in which a device is not used, how do I know it was minimally invasive? I need a resource I can cite. Thanks!