A transport card or transport pass was a permit issued by the Ardanan citizens who inhabited the city of Stratos. This permit allowed Troglytes to enter the city and move about it without question.
In 2269, Plasus questioned a Troglyte who had been found without a transport card. The man claimed it had been lost when Plasus's sentinels attacked him.
Later, Vanna told James T. Kirk that they would need one to leave Stratos. (TOS: "The Cloud Minders")