302100Z SARS34 RUMS 302100
WMO analysis header
302100 is the time group
SARS34
is a apecific data format
TTAAii
where TT is product type, such as AB for weather text summaries, or SA for surface observations (METARs);
where AA is the region of the origin of the report, such as AK for Alaska, or US for the United States;
and where ii is the report number.
So we have SA (surface observation for Aviation routine reports) RS is the region Russia(west) and 34 is the report number.
CCCC
where CCCC is the 4 letter station identifier of the source of the report; such as KDSM for Des Moines, IA or KDEN for Denver, Colorado.
RUMS is Russia Moscow.
Now that I've told you I have to kill you!!
P.S. more info can be found in WMO No. 386 Manual on the Global Telecommunication System
Part II - Operational Procedures for the GTS
or here:
http://www.wmo.int/pages/prog/www/oi...t2_AttII05.pdf