vacation bid

Do F/T drivers bid by their hire date or their F/T seniority date?
I was told it goes by the hire date..Any info would be appreciated seeingI cant find any info on it in the union book..

FT Date for vacation bidding

Bid in order of FT seniority date.
Vacation weeks (amount) by start date.

You aquire number of vacation weeks off by years of service. You mark your vacations as a full time driver by your seniority date as a driver.