What kind of thread is sold by openbuilds: ACME or Metric?

What does ACME Metric Lead screw mean? The designation TR8*8 means a Trapezoidal Metric lead screw with 8mm diameter and 8 mm pitch and a thread angle of 30 degrees. ACME means a thread angle of 29 degrees. So what kind of lead screw is beeing sold by the openpartsbuildstore ( and all the others)??
Thanks in advance

Michael
Here a link
Metric ACME Lead Screw - A Common Engineering Error Most People Make for Trapezoidal Metric Threads

 

Thanks for the information and the link. I searched for such information but did not find it.
Michael