Observations may contain restricted data that prevents redistribution of observations
or data that could be used deduce the observation such as obserbation-analyhsis.

Restricted data did not exist before 2003.

Some restrictions are of the stored the EXPRSRD element in the bufr files


Below they all are. The EXPRSRD element is the number of hours the restriction is in effect. 
If it's missing, that means forever. Bits are numbered from left to right.

0-35-200 - RSRD
Restrictions on redistribution
Bit number	Meaning
1    (512)      No redistribution allowed
2    (128)      Can redistribute to any U.S. government agency
3    (64)       Can redistribute to any U.S. research group
4    (32)       Can redistribute to any U.S. educational institution
5    (16)       Can redistribute to any U.S. government agency within NOAA
6-8	        Reserved
All 9	        Missing value (forever)

Some restricted data have time limits.  For example aircraft often have a 48 hour
limit when restricted.  After 48 hours, this data is unrestricted.

Japanese ships can be restricted, and the ship identification need to be removed.


Status: 9/2024
  The diagnostic files from before 2003 can be distributed.
  Software to remove the restricted data from newer diagnostic files should be written.
  We want to make the diagnostic files easily available.  However, wants and needs
  are two different things. Getting CORe operational is the highest priority.
  Documentation and getting third party archive sites up to speed is next in line.