Here is a list of all files with brief descriptions:

check_ioda_nc.py
DescendingSort.h
Distribution.cc
src/distribution/Distribution.h
test/distribution/Distribution.h
DistributionFactory.cc
DistributionFactory.h
InefficientDistribution.cc
InefficientDistribution.h
instantiateObsLocFactory.h
ioda_cpplint.py
ioda_obs_example_mod.F90
IodaIO.cc
src/io/IodaIO.h
test/io/IodaIO.h
IodaIOfactory.cc
IodaIOfactory.h
IodaTrait.h
IodaUtils.cc
IodaUtils.h
LocalObsSpace.h
LocalObsSpaceParameters.cc
LocalObsSpaceParameters.h
NetcdfIO.cc
NetcdfIO.h
ObsData.cc
ObsData.h
ObsDataVector.h
ObsLocGC99.cc
ObsLocGC99.h
ObsSpace.cc
ObsSpace.Example.interface.F90
obsspace.F90
src/ObsSpace.h
test/ioda/ObsSpace.h
obsspace_f.cc
obsspace_f.h
obsspace_interface.f
obsspace_mod.F90
src/core/ObsSpaceContainer.h
test/core/ObsSpaceContainer.h
ObsVector.cc
src/ObsVector.h
test/ioda/ObsVector.h
RoundRobin.cc
RoundRobin.h
TestDescendingSort.cc
TestDistribution.cc
TestIodaIO.cc
TestIodaLocalObsSpace.cc
TestIodaObsSpace.cc
TestIodaObsVector.cc
TestLocalObsSpace.cc
TestLocations.cc
TestObsErrorCovariance.cc
TestObsSpace.cc
TestObsSpaceContainer.cc
TestObsVector.cc
timeIodaIO.cc
timeIodaIO.h