1673 CDX Internet Archive Index Text (Structured) 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. 1 Digital Preservation Department / The National Archives 14 Jan 2016 22 Sep 2020 fmt/869 PUID cdx File extension 1229 CDX Archive Index variant 1 BOF: <field delimiter (usually space)>CDX<field delimiter (usually space)>, 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. 1 Absolute from BOF 0 0 2043445820 1751 CDX Archive Index variant 2 BOF: 'CDX' <field delimiter (usually space)>, 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 1 Absolute from BOF 0 0 43445820