[Elmo]

Here is what I pulled from SWA tonight:

Boarding Procedure
Each Customer will be issued a boarding pass grouped by A, B, or C (in that order) based on when the Customer checked in online at southwest.com, at the Skycap Podium, Ticket Counter, Departure Gate, or E-Ticket Check-In kiosk (where available).

Prior to general boarding, Customers with disabilities or unaccompanied children between the ages of five and 11 may preboard. Customers who choose to preboard cannot sit in an emergency exit seat.

Effective October 2 in all Southwest cities, an adult traveling with a child four years old or younger will board between the “A” and “B” boarding groups.

If you have an “A” boarding pass, please feel free to board with that boarding group. With an all-jet fleet outfitted with comfortable, leather seats, our families with small children are easily accommodated together.
Because Southwest Airlines maintains an open-seating policy, general-boarding Customers may sit in any open or unclaimed seat. Customers holding boarding pass "A" will begin general boarding, followed by Customers with boarding pass "B," and then "C." General-boarding Customers who choose an emergency exit seat must meet all requirements set forth by the Federal Aviation Administration and Southwest Airlines.