REQDOC
Request for document message

UNH M Message header

BGM M Beginning of message

DOC M Document/message details

DTM M Date/time/period

FTX C Free text

SG1 C
RFF
DTM

SG2 M
NAD
LOC
SG3

SG4 M
LIN
GIS
DTM
...

UNT M Message trailer