<?xml version='1.0' encoding='utf-8'?>
<PRONOM-Report xmlns="http://pronom.nationalarchives.gov.uk">
  <report_format_detail>
    <FileFormat>
      <FormatID>2810</FormatID>
      <FormatName>Common Data Format dotCDF</FormatName>
      <FormatVersion>2.0-2.5</FormatVersion>
      <FormatAliases> </FormatAliases>
      <FormatFamilies> </FormatFamilies>
      <FormatTypes>Dataset</FormatTypes>
      <FormatDisclosure> </FormatDisclosure>
      <FormatDescription>Common Data Format is a library and toolkit that was developed by the National Space Science Data Center (NSSDC) at NASA, used for the storage and processing of multi-dimensional datasets. The ‘dotCDF’ file as described in the specification refers specifically to the filetype with extension .cdf. The dotCDF file may be a standalone file containing everything it needs, or it may have companion ‘variable’ files with the extension .vX, where X represents an incrementing numeric value, e.g. .v0, .v1 etc.
This entry covers versions 2.0-2.5. Version 2.6 onwards introduced optional compression, and earlier versions require further research.</FormatDescription>
      <BinaryFileFormat> </BinaryFileFormat>
      <ByteOrders> </ByteOrders>
      <ReleaseDate> </ReleaseDate>
      <WithdrawnDate> </WithdrawnDate>
      <ProvenanceSourceID>244</ProvenanceSourceID>
      <ProvenanceName>Preservica / Preservica</ProvenanceName>
      <ProvenanceSourceDate>11 Apr 2024</ProvenanceSourceDate>
      <ProvenanceDescription> </ProvenanceDescription>
      <LastUpdatedDate>11 Apr 2024</LastUpdatedDate>
      <FileFormatIdentifier>
        <Identifier>fdd000226</Identifier>
        <IdentifierType>Library of Congress Format Description Identifier</IdentifierType>
      </FileFormatIdentifier>
      <FileFormatIdentifier>
        <Identifier>fmt/1948</Identifier>
        <IdentifierType>PUID</IdentifierType>
      </FileFormatIdentifier>
      <FileFormatIdentifier>
        <Identifier>Q1116060</Identifier>
        <IdentifierType>Wikidata QID Identifier</IdentifierType>
      </FileFormatIdentifier>
      <ExternalSignature>
        <ExternalSignatureID> </ExternalSignatureID>
        <Signature>cdf</Signature>
        <SignatureType>File extension</SignatureType>
      </ExternalSignature>
      <InternalSignature>
        <SignatureID>2293</SignatureID>
        <SignatureName>CDF 2.0-2.5</SignatureName>
        <SignatureNote>BOF; Offset: 0; Magic number 0x0000FFFF 0x0000FFFF, then a 4 byte variable value representing the size of the ‘CDF Descriptor Record’, followed by the 4 byte ‘RecordType’, which for the CDF Descriptor Record is 0x00000001. There are additional elements in the CDF Descriptor Record that may be used to strengthen the signature is required, and potentially to further divide into separate sub-versions if required.
Specifications can be found on the Internet Archive: https://web.archive.org/web/20150922063622/http://nssdcftp.gsfc.nasa.gov/standards/cdf/doc/ or https://cdaweb.gsfc.nasa.gov/pub/software/cdf/dist/obsolete/</SignatureNote>
        <ByteSequence>
          <ByteSequenceID>1</ByteSequenceID>
          <PositionType>Absolute from BOF</PositionType>
          <Offset>0</Offset>
          <MaxOffset>0</MaxOffset>
          <IndirectOffsetLocation> </IndirectOffsetLocation>
          <IndirectOffsetLength> </IndirectOffsetLength>
          <Endianness> </Endianness>
          <ByteSequenceValue>0000FFFF0000FFFF{4}00000001</ByteSequenceValue>
        </ByteSequence>
      </InternalSignature>
      <RelatedFormat>
        <RelationshipType>Is previous version of</RelationshipType>
        <RelatedFormatID>2812</RelatedFormatID>
        <RelatedFormatName>Common Data Format dotCDF</RelatedFormatName>
        <RelatedFormatVersion> </RelatedFormatVersion>
      </RelatedFormat>
    </FileFormat>
  </report_format_detail>
</PRONOM-Report>