Is the phrase "yellow card" slang for a female body part?

In Hemmingway's The Sun Also Rises, Braddocks says of Georgette that:

"She was rather splendid, you know. Showed her yellow card and demanded the patronne's daughter's too."

But they weren't playing soccer, so what did he mean? My best guess is that it means that Georgette showed something immodest and demanded the patronne's daughter do likewise.

I found an explanation of yellow card in Peter Hays, The Critical Reception of Hemingway's The Sun Also Rises (2011):

But on the subject of Parisian whores, [the critic Michael] Reynolds makes an important correction. At the bal musette Georgette flashes her yellow card, her license as a prostitute, a license that necessitated regular examinations for venereal disease (SAR 36). When she tells Jake, "Everybody's sick. I'm sick, too" (SAR 23), it is not venereal disease to which she is referring, as many readers and critics have assumed. As Reynolds says, "it is not sickness of the flesh but of the spirit, and in that sense everybody in the novel is, indeed, sick" (76).

It is thus not a slang term. Instead, it refers to what is, literally, a yellow card issued by the government and affirming that the government's medical authorities have checked the bearer within the past year for venereal diseases and found that she did not (at that time) have any.

There were a few versions of a movie called "The Yellow Ticket" http://www.imdb.com/title/tt0009842/ (two in 1918 and one in 1931) about a Jewish girl who becomes a prostitute to save her family. The "yellow ticket" refers to the card given to single women that allowed them to travel beyond certain geographical limits, but implied that they were, um, "working girls".