Leica GPS1200 Series Technical Reference Manual page 1365

Examples
NMEA Message Formats
Field Description
<LF> Line Feed
Standard Talker ID
$GNGSA,A,3,01,11,14,17,19,20,24,28,,,,,1.5,0.9,1.2*26
$GNGSA,A,3,65,66,67,81,,,,,,,,,1.5,0.9,1.2*29
User defined Talker ID = GN
$GNGSA,A,3,01,11,14,17,19,20,23,24,28,,,,65,66,67,81,,,,,,,,,1.2,0.7,1.0*27
GPS1200 1365