Record Type Descriptions

A brief overview of each of the record types follows. See Section 2.4 for the details of each record type.

TEST

provides all of the system-dependent information which is necessary for interpreting the bit patterns in the subsequent dataset records. It also contains a magic number which identifies that the dataset is in the df format.

OBJDESC

describes a data object. It contains general information needed by the other record types.

AUDIT

provides for an audit trace of data objects which have been derived from other data objects. See Section 2.3.4 for a discussion and examples of the audit tree.

INFOSPEC

is a record type that contains unrestricted user-specified information. See Section A.2.6 for details.

COMMENT

contains user-specified information in the form of an 80-character string. This allows for human-readable comments.

DIMSPEC0

specifies how the Level 0 dimensions of the data object are indexed.

DIMSPEC1

specifies how the Level 1 dimensions of the data object are indexed.

DIMSPEC2

specifies how the Level 2 dimensions of the data object are indexed.

DIMSPEC3

specifies the number of DESCRIP3 records for the Level 3 dimensions of the data object.

DESCRIP0

describes the data or its component parts that each Level 0 dimension represents.

DESCRIP1

describes each Level 1 dimension. This is the authoritative descriptor for a Level 1 dimension.

DESCRIP2

describes each Level 2 dimension. This is the authoritative descriptor for a Level 2 dimension.

DESCRIP3

describes each Level 3 dimension. This is the authoritative descriptor for a Level 3 dimension.

DESCRIP

provides an alternative, nonauthoritative description of any Level 1, Level 2, or Level 3 dimension. These descriptors are a means of ``renaming'' grid points in terms which may be more meaningful to the dataset's users.

DESCVAL

contains the grid point values corresponding to a dimension described by a DESCRIP1, DESCRIP2, DESCRIP3, or DESCRIP record type.

DESCSUP

contains supplementary information about a given dimension. For example, if a dimension corresponds to an x or y coordinate in a geographical map projection, then the coordinates of the map pole would be specified here.

BADVAL

specifies how missing or bad data are to be flagged in the data records. The absence of BADVAL records implies that there are no bad or missing data.

PROCSPEC

provides a means for attaching special notes or processing flags to subsets of the data. See Section 2.3.5 for more details.

PROCFORM

specifies the format of the processing information in the associated PROCVAL record. If the processing method used requires no information values, then this record will not be present.

PROCVAL

specifies the processing information as indicated in the associated PROCSPEC record. If the processing method used requires no information values, then this record will not be present.

PROCDUP

allows for processing information specified by a previous Procgroup to be applied over a different range of dimensions. This record provides a shorter alternative to duplicating an entire Procgroup with a different set of coordinate values.

AUXSPEC

specifies the nature of the auxiliary information and how it applies to the data. See Section 2.3.3 for more details.

AUXRANGE

specifies the dimensions the auxiliary information refers to and which dimensions it varies over.

AUXVAL

gives the actual auxiliary information itself.

AUXSUP

gives certain supplemental values which may be needed to interpret the auxiliary values.

PAKSPEC

describes the method used to pack the data in the data object.

PAKFORM

specifies the format of the packing information in the associated PAKVAL record. If the packing method used requires no parameters, and no bad data are present, then this record will not be present.

PAKVAL

specifies the packing information as indicated in the PAKSPEC record. If the packing method used requires no parameters, and no bad data are present, then this record will not be present.

COMPSPEC

describes the compression method used to compress the data in the data object.

COMPLEN

gives the length of each COMPDAT record of compressed data.

COMPFORM

specifies the format of the compression information in the COMPVAL record. If the compression algorithm requires no parameters, then this record will not be present.

COMPVAL

specifies the compression information as indicated in the COMPSPEC record. If the compression algorithm requires no parameters, then this record will not be present.

REGDAT

contains the actual data values, if the data have not been packed or compressed. Each record contains the data over a single set of values of the Level 2 dimensions: Level 1 dimensions vary within a REGDAT record, while Level 2 dimensions vary between REGDAT records.

PAKDAT

contains the actual packed data values, if the data have been packed. PAKDAT has the same structure (number of records, number of data values in each record) as a REGDAT record, but it contains packed data.

COMPDAT

contains the actual compressed data values, if the data have been compressed. Usually there will be only one COMPDAT record.