FME considers a folder of TIGER/Line data files to be a dataset. Optionally the *.rt1 file may be used as a dataset. The folder may contain TIGER/Line files for one or more regions. The regions are counties, or county equivalents. Each county consists of a series of files with a common basename, and different extensions. For instance, county 1 in state 26 (Michigan) consists of the following file set in Tiger98.
TGR26001.RT1 TGR26001.RT2 TGR26001.RT3 TGR26001.RT4 TGR26001.RT5 TGR26001.RT6 TGR26001.RT7 TGR26001.RT8 TGR26001.RT9 TGR26001.RTA TGR26001.RTC TGR26001.RTH TGR26001.RTI TGR26001.RTP TGR26001.RTR TGR26001.RTS TGR26001.RTZ