Clarification:
You don't get mileage credit for free bump vouchers. Your DM number isn't even listed on your boarding pass, although your status is listed in the system and on your boarding pass so you can take advantage of seating and boarding privileges.
However, tickets purchased in whole or in part with money (e.g., $600) vouchers -- only given on international flights (?) -- do earn mileage.
[This message has been edited by davohuang (edited 02-15-2001).]