But here, each SEPTA employee who sells a pass judges whether the rider looks M or F, and if a bus driver or train conductor disagrees, the pass could be confiscated.
Adamor and fellow organizers at Riders Against Gender Exclusion (RAGE), a grassroots group formed two years ago, say the stickers make life difficult, degrading, and dangerous for anyone whose appearance is nonconforming.
And a growing number of young transgender people are intent on identifying as androgynous, he said, to emphasize that gender distinctions are unnecessary.
Consider the case of Charlene Moore-Arcila.
In 2006, when Moore-Arcila was transitioning from male to female, she boarded a SEPTA bus at the end of a long day and was confronted by a driver who said her appearance did not jibe with the sticker on her pass. He ordered her to pay an additional $2, and Moore-Arcila, too exhausted to argue, complied.
She complained later, though, and her case is pending before the city's Commission on Human Relations. SEPTA contends that as a state agency, it is not bound by the city's Fair Practices Act.
In another long-pending case, SEPTA was found in violation of the Americans With Disabilities Act for not installing elevators at its City Hall station. Still, the agency said this month it may seek more time to comply.
Meanwhile, RAGE stepped up its actions last year, collecting testimony from about 20 transgender riders who said they were questioned by bus drivers, publicly mocked, and called names.
Such complaints will fall by the wayside soon enough, Williams said, when SEPTA replaces passes with new technology, most likely something like the smart-card system used in New York City. There, riders buy refillable cards loaded with whatever number of trips they wish. If those cards are shared, at least each ride is paid for.
Whatever the new payment system, Williams said, it won't use gender designations. And with a $175 million loan agreement finally in place, Williams said, the agency hopes to hire a contractor by June and have the system running within three years.
RAGE organizer Max Ray said SEPTA had dangled the smart-card system as a curative carrot before.
"SEPTA told us in October 2009 that a new system would be in place within the year," Ray said. "So we don't have a lot of faith in their timelines."
Besides, he said, the sticker system is not technology-based, so it is unrelated to the use of smart cards.
Still, the SEPTA board is adamant.
"The board voted to continue with it [the stickers] until a full change takes place. No more talk at the board level is planned," Williams said. "The decision has been made."
RAGE vows to stay in the fight by asking allies and public officials to join its quest for a Bill of Rights to protect all riders.
When SEPTA started the sticker system in 1981, transgender issues were probably not on its radar.
"So many times in the past, a government or bureaucratic system created a policy in which gender was unthinkingly made a part of a document or database, with unintended consequences like this," said Harper Jean Tobin, a lawyer with the National Center for Transgender Equality.
But in the last decade, transgender individuals organized locally and nationally, Tobin said, calling attention to seemingly innocuous policies that trample their civil rights.
Now, Tobin said, most bureaucracies know better. The transgender community is being heard and accommodated, she said, with changes that are nothing short of seismic.
In 2010, the U.S. Department of State made it easier for transgender individuals to change the name and gender on their passports.
"When you see the State Department accommodating transgender," Tobin said, "that's a big signal. It's huge."
Other state and local agencies changed their policies last year, too, making it easier to change Social Security cards, birth certificates, and driver's licenses.
At the University of Pennsylvania, student medical insurance now covers gender-reassignment treatment, and the IRS allows medical deductions for such treatment.
The International Olympic Committee accommodates transgender athletes, as does the School District of Philadelphia, case by case. And in 2010, the NCAA let Kye Allums become the first openly transgender athlete to play women's Division I basketball. Allums, who was born female and is living as a male, is postponing hormone treatment for the change.
SEPTA just has to stop adding stickers to its passes, said Amara Chaudhry, director of legal services at the Mazzoni Center in Center City, which offers LGBT-focused health care and legal services. And that change could take place tomorrow.
Padilla said people had to get past discussing the individual circumstances in which discrimination might be excused.
"The question is," she said, "how can we end discrimination?"
Contact staff writer Dianna Marder at 215-854-4211 or email@example.com. Read her recent work at http://go.philly.com/diannamarder