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Introduction

In <cite>Automatic Automatic Format Identification using PRONOM and DROID</cite>DROID, Adrian Brown defines a "data format" as:<blockquote>The

The internal structure and encoding of a digital object,

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which allows it to be processed, or to be rendered in human-accessible

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form.

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Note that this implies more than just knowing the common name of a Bitstream's format, e.g. "Adobe PDF". That name actually describes a family of formats. In order to know exactly how to recover the intelligence in a particular Bitstream, you'd want to know which specific version of PDF it is: later versions have features not found in earlier ones. The "internal structure and encoding" imposed by a data format is usually defined in exacting detail by a format specification document, and/or by the software applications that produce and consume that format.

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This is the default algorithm that is implemented by FormatIdentifier.identifyFormat() methods that simply call the FormatHit's addToResults() method on each hit they develop.

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1. Start with an empty results list.
2. Call the FormatIdentifier.identifyFormat() method of each plugin in the sequence in turn:
   • Passing it the Bitstream and list of accumulated results so it can add new results.
   • If it has a better-confidence match than the current head of the list, that hit becomes the new head of the list.
   • Otherwise the hit gets appended to the end of the list.
3. When finished, the head of the list is the best format match.

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