code|description
B|Baseline control
C|Concurrent control
I|Insufficient
K|Control data is presented but without accompanying methodology
M|Multiple control types
ME|Multiple entries
NA|Unspecified
NR|Not reported
O|Control outside of primary exposure system
OK|Used to group mults from reference manager conversion
P|Positive control
S|Satisfactory
U|Unsatisfactory
V|Carrier or solvent control
Z|No controls were used in the study
