Type 1. First introduced. Single line VOCo. Used in 5 offices.
Type 2. Two lines VO/Co. Most widely used of the VOCo perfins. Used in 12 offices.
Type 3. Single line VOCo. Used in 9 offices.
Withdrawn from service.
Thought possible to distnguish between the different offices by the perfin holes missing in "C"
History of Company