Is our progressive discipline procedure confusing for the staff?

Q: “My company is in 36 states including California, Colorado and New York. The company has three stages of progressive discipline – Verbal/Written/Final. Managers tend to issue Performance Improvement Plans (PIP) and count it as part of the progressive discipline without designating if it is part of the (Verbal/ Written/Final Warning). My concern is that employees could [feel] angst by this practice because it is not documented in the policy as being an independent stage of progressive discipline — meaning if only a PIP document is issued to an employee, how do they know if they are facing disciplinary action, or what stage of disciplinary action? What do you suggest?" – Anonymous, Texas