JFDF Specification:

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INDEX FILE (XXXXX.jfdf)
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//int:    "JFDF" - magic
//int:    JFDF version (1)

int:    size of titles tokens (in bytes)
int:    size of titles tokens (in bytes)

Tokens: [Titles]
Tokens: [Bodies]
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TOKENS STRUCTURE
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int:   token 1 start
int:   token 1 end

int:   token 2 start
int:   token 2 end
...
int:   token N start
int:   token N end
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