What is the content of IO such as GPS data out and GPS NMEA

Hi

I am using the LabVIEW Communications LTE Framework Application, there are some IO as GPS data, GPS NMEA, GPS NMEA Valid, ect., I find out that the out put of GPS data and GPS NMEA are 8 bits signal, but I don't  know what  is the the contents of this I/Os, and their update rate. I cannot find user manual on NI help. Can anyone help to explain more details about them?  

//Junshi