SVF Design Criteria

Understanding the design criteria for SVF helps in understanding how the format works, how it can be used, and how it relates to other vector formats.

General

• Web-centric
  Contains hyperlinks, is compact and streamable.
• Simple to write
  Most information is optional. An SVF file could consist of nothing but the intro string and a line.
• Simple to read
  Single way to encode most information. Limited set of commands.
• Simple to display
  It should be easy to build a low-overhead viewer that completely supports SVF.
• Comprehensive
  While it should be restricted to a small set of features for simplicity, it should also be complete enough to accurately represent such common vector drawings as maps, flowcharts, and CAD (e.g. AutoCAD and MicroStation).
• Compact
  Accomplished using variable precision and current state.
• Extensible
  Accomplished through custom user data, embedded objects with arbitrary MIME types, and the Extension command for encapsulating future SVF commands.
• Streamable
  A viewer shouldn't have to make an initial pass through the file to figure out details necessary for display or translation. Information can be used as soon as it's read - it doesn't depend on anything after it in the file. Accomplished through extents and other information being specified in the header.
• Portable
  Should be machine and operating system independent. For example, the font table can specify alternate information for systems without the desired font.
• International
  All strings are stored in Unicode.
• Representational not Structural
  For simplicity, SVF is intended to be a simple graphical representation. It doesn't contain detailed organizational information.
• Database links
  Through object ids, objects and groups of objects can be tied back to the original drawing or database.

SVF/XML Design Criteria

• Contains same information as binary version
  Must be able to easily translate between the XML and binary versions of SVF.
• Streamable
  Information can be used as soon as it's read - it doesn't depend on anything after it in the file.
• Follows XML standards and recommendations
  Must be human readable and writable. Must be able to work with other XML standards.
• Simple to embed in other XML documents
  Very little markup is required for minimal SVF information.

SVF2 Design Criteria

• Backward Compatibility
  All SVF1.1 files should automatically be valid SVF2. New commands should follow same general rules as SVF1.1.
• More complete
  SVF1.1 supported a reasonable subset of vector descriptions. Based on feedback from many companies and individuals, SVF2 was designed to more completely represent a wide range of vector information.