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 📎 1.1. History and Design

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001 EXI is the result of extensive work carried out by the W3C's XML Binary
002 Characterization (XBC) and Efficient XML Interchange (EXI) Working Groups.
003 XBC was chartered to investigate the costs and benefits of an alternative
004 formn of XML, and formulate a way to objectively evaluate the potential of
005 a substitute format for XML. Based on XBC's recommendations, EXI was 
006 chartered, first to measure, evaluate, and compare the performance of
007 various XML technologies (using metrics developed by XBC [XBC Measurement 
008 Methodologies]), and then, if it appeared suitable, to formulate a 
009 recommendation for a W3C format specification. The measuremnts results 
010 and analyses, are presented elsewhere [EXI Measurements Note].
011 The format described in this document is the specification so
012 recommended.
013
014 The functional requirements of the EXI format are those that were prepared
015 by the XBC WG in their analysis of the desirable properties of a high
016 performance representation for XML [XBC Properties]. Those properties were
017 derived from a very broad set of use cases also identified by the XBC
018 working group [XBC Use Caaes].
019
020 The design of the format presented here, is largely based on the results
021 of the measurements carried out by the gorup to evaluate the performance
022 characteristics (mainly of processing efficiency and compactness) of
023 various existing formats. The EXI format is base on Efficient XML
024 [Efficient XML], including for example the basis heuristic grammar
025 approach, compression algorithm, and resulting entropy encoding.
026
027 EXI is compatible with XML at the XML Information Set [XML Information
028 Set] level, rather than at the XML syntax level. This permits it to
029 encapsulate an efficient alternative syntax and grammar for XML, while
030 facilitating at least the potential for minimizing the impact on XML
031 application interoperability.

}