<?xml version="1.0" encoding="utf-8"?>
<PRONOM-Report xmlns="http://pronom.nationalarchives.gov.uk">
  <report_format_detail>
    <FileFormat>
      <FormatID>1673</FormatID>
      <FormatName>CDX Internet Archive Index</FormatName>
      <FormatVersion>
      </FormatVersion>
      <FormatAliases>
      </FormatAliases>
      <FormatFamilies>
      </FormatFamilies>
      <FormatTypes>Text (Structured)</FormatTypes>
      <FormatDisclosure>
      </FormatDisclosure>
      <FormatDescription>A CDX file consists of individual lines of text, each of which summarizes a single web document. 
The first line in the file is a legend for interpreting the data, and the following lines contain the data for referencing the corresponding pages within the host. The CDX signatures use a field delimiter character which is assumed to be a space character, however please contact the PRONOM team should you encounter CDX index files where the delimiter is different.</FormatDescription>
      <BinaryFileFormat>
      </BinaryFileFormat>
      <ByteOrders>
      </ByteOrders>
      <ReleaseDate>
      </ReleaseDate>
      <WithdrawnDate>
      </WithdrawnDate>
      <ProvenanceSourceID>1</ProvenanceSourceID>
      <ProvenanceName>Digital Preservation Department / The National Archives</ProvenanceName>
      <ProvenanceSourceDate>14 Jan 2016</ProvenanceSourceDate>
      <ProvenanceDescription>
      </ProvenanceDescription>
      <LastUpdatedDate>22 Sep 2020</LastUpdatedDate>
      <FormatNote>
      </FormatNote>
      <FormatRisk>
      </FormatRisk>
      <TechnicalEnvironment>
      </TechnicalEnvironment>
      <FileFormatIdentifier>
        <Identifier>fmt/869</Identifier>
        <IdentifierType>PUID</IdentifierType>
      </FileFormatIdentifier>
      <ExternalSignature>
        <ExternalSignatureID>1791</ExternalSignatureID>
        <Signature>cdx</Signature>
        <SignatureType>File extension</SignatureType>
      </ExternalSignature>
      <InternalSignature>
        <SignatureID>1229</SignatureID>
        <SignatureName>CDX Archive Index variant 1</SignatureName>
        <SignatureNote>BOF: &lt;field delimiter (usually space)&gt;CDX&lt;field delimiter (usually space)&gt;, followed by CDX options as described here: https://archive.org/web/researcher/cdx_file_format.php
For signature strength we currently assume the field delimiter will be a space character (hex 0x20) rather than a wildcard, with scope to add further delimiters as they are encountered.</SignatureNote>
        <ByteSequence>
          <ByteSequenceID>1500</ByteSequenceID>
          <PositionType>Absolute from BOF</PositionType>
          <Offset>0</Offset>
          <MaxOffset>0</MaxOffset>
          <IndirectOffsetLocation>
          </IndirectOffsetLocation>
          <IndirectOffsetLength>
          </IndirectOffsetLength>
          <Endianness>
          </Endianness>
          <ByteSequenceValue>2043445820</ByteSequenceValue>
        </ByteSequence>
      </InternalSignature>
      <InternalSignature>
        <SignatureID>1751</SignatureID>
        <SignatureName>CDX Archive Index variant 2</SignatureName>
        <SignatureNote>BOF: 'CDX' &lt;field delimiter (usually space)&gt;, followed by CDX options as described here: https://archive.org/web/researcher/cdx_file_format.php. This format could potentially be strengthened if necessary with the inclusion of one or more of the CDX options, which are to date an alphabetic character (upper or lower case, a-z, A-Z with a few exceptions) or the hash value</SignatureNote>
        <ByteSequence>
          <ByteSequenceID>2029</ByteSequenceID>
          <PositionType>Absolute from BOF</PositionType>
          <Offset>0</Offset>
          <MaxOffset>0</MaxOffset>
          <IndirectOffsetLocation>
          </IndirectOffsetLocation>
          <IndirectOffsetLength>
          </IndirectOffsetLength>
          <Endianness>
          </Endianness>
          <ByteSequenceValue>43445820</ByteSequenceValue>
        </ByteSequence>
      </InternalSignature>
    </FileFormat>
    <SearchCriteria>Criteria</SearchCriteria>
  </report_format_detail>
</PRONOM-Report>
