This would be your company policy.This is the wording from the policy.
Company seniority in the affected job classification is used to determine which employee(s) is displaced. The
employee(s) with the lowest company seniority in the particular job classification(s) affected is asked to make a
decision regarding employment status based on available options outlined on the Workforce Staffing Decision
form. Volunteering to be identified as a displaced employee is not allowed.
Under our contract when you bumped into another classification you carried your company seniority and it all became your new seniority in that classification.
This was in the (Carolina's only) I don't know of anywhere else this applied.