Page "Simple API for XML" Paragraph 5

Some implementations do not neatly fit either category: a DOM approach can keep its persistent data on disk, cleverly organized for speed ( editors such as SoftQuad Author / Editor and large-document browser / indexers such as DynaText do this ); while a SAX approach can cleverly cache information for later use ( any validating SAX parser keeps more information than described above ).

Such implementations blur the DOM / SAX tradeoffs, but are often very effective in practice.