Card Index to Pass****t Applications

I'm researching family from Germany who emigrated to the U.S. in the 
mid-to-late 19th century.

I've found that the Family History Centers (LDS) have microfilms entitled 
"Card Index to Pass****t Applications", which are organized by date and 
surname.  Before I go to the trouble of going to the nearest FHC and 
ordering the films, can anyone tell me what sort of information I'm likely

to find on these index cards?

Thanks in advance,

t