The _C_METADATAXML_ is an optional field to store extra information about the concept in xml format. It is currently used to describe value metadata associated with a lab finding.

The next several fields, _C_FACTTABLECOLUMN, _C_TABLENAME, _C_COLUMNNAME, _C_OPERATOR, and C_DIMCODE are used to help construct a metadata SELECT SQL query that runs behind the scenes. The intent of this query is to link the dimension tables to the fact table for a given term. As a result every metadata SELECT SQL statement should return a fact table key.
In general the metadata SELECT SQL that is composed looks like the following:
SELECT C_FACTTABLECOLUMN
FROM C_TABLENAME
WHERE C_COLUMNNAME C_OPERATOR C_DIMCODE

For most CONCEPT_DIMENSION based queries this will appear as:
SELECT CONCEPT_CD
FROM CONCEPT_DIMENSION
WHERE CONCEPT_PATH LIKE '\Diagnoses\Circulatory system{color:#808080}%'

For a PATIENT_DIMENSION based query this may appear as:
SELECT PATIENT_NUM
FROM PATIENT_DIMENSION
WHERE BIRTH_DATE BETWEEN 'getdate() AND GETDATE() – 365.25(10) '

For a VISIT_DIMENSION based query this may appear as:
SELECT ENCOUNTER_NUM
FROM VISIT_DIMENSION
WHERE INOUT_CD = 'I'

For a PROVIDER_DIMENSION based query this may appear as:
SELECT PROVIDER_ID
FROM PROVIDER_DIMENSION
WHERE PROVIDER_PATH LIKE '\Providers{color:#0000ff}Emergency{color:#808080}%'