也许是EAD的别名吧。google 的结果：

1. Unexpired Temporary Resident Card (INS Form I-688)
2. Unexpired Employment Authorization Card (INS Form I-688A)
3. Unexpired Employment Authorization Document issued by the INS which contains a photograph (INS Form I-688B)

http://64.233.161.104/search?q=cache:rwPb0WsAlt0J:www.ma.utexas.edu/dev/math/Graduate/New_Students/Official_Documents.html+INS+Form+I-+688A&hl=en&gl=us&ct=clnk&cd=6

其实不用担心，带了EAD card就应该没有问题了。