Embedded quality control fields use bit-packing to store the results from multiple quality control tests into a single companion quality control (QC) field. The extra code required to fully utilize the companion QC fields may seem daunting at first, but is actually quite compact.
Understand the tests performed
Each datastream describes the tests performed on the data values in the netCDF header, including the description of the bit number correlating to the test. The first step in using the companion QC field is to choose which tests to use for masking the data.
For example, the direct normal broadband companion quality control has six tests performed on the data. Each bit is described with a description attribute (i.e. qc_direct_normal_broadband:bit_1_description) describing the test associated with each bit. If a value meets the test criteria, that bit will be set.
To use the companion field QC decide which tests are relevant to your analysis and will be used for masking data from analysis.