In theory, the precise coordinates for these samples would be determined and added to the database at a later date. The submission of geocoding with samples was mandatory for some fields and optional for others. Therefore, the completeness of geocoding can vary. In addition, most geocodes were not checked for completeness, accuracy, or validity during data entry into the database. The Material Code designates the type of sample media analyzed.
Many times concentrate samples can also be determined from the contents of the description field.
The description field is the most useful secondary field for identifying coal samples in the database. The analytical data on coal samples includes data on both whole coal and coal ash. For some semi-quantitative spectrographic methods, an N was used when an element concentration could not be detected and an L was used when the element could be detected but the concentration was below determination limits that could confidently be reported. However for other analytical methods, a concentration below the determination limits of the method may be qualified with either an N or an L depending upon the method, the analyst, or the laboratory. It has not been possible to do a complete quality control check on the entire database.