Question about how seniority in a class is determined, again.....

I've seen some posts that state the higher SSN gets the higher seniority. But I found this in DAL's PWA:

"New-hires will be assigned seniority numbers on the basis of the last four digits of each individual’s social security number. Individuals with the higher numbers will be assigned the lowest seniority numbers." -Section 20, B., 2., b.

Am I reading it wrong or does the lower SSN get a higher seniority?

Thanks