Exhibit A: MS Word "fast save" format: https://web.archive.org/web/20160308183811/http://1017.songtrellisopml.com/whatsbeenwroughtusingpiecetables https://web.a

Exhibit A: MS Word "fast save" format: https://web.archive.org/web/20160308183811/http://1017.songtrellisopml.com/whatsbeenwroughtusingpiecetables https://web.archive.org/web/20160308183811/http://1017.songt... https://www.joelonsoftware.com/2008/02/19/why-are-the-microsoft-office-file-formats-so-complicated-and-some-workarounds/ https://www.joelonsoftware.com/2008/02/19/why-are-the-micros... From CS perspective, it's an impressive feat of engineering. They used persistent data structures to optimize in-memory operations, and essentially a write-ahead log of these same structures to optimize commits to disk. They also created "OLE" technology in the OS+libraries to support embedding live documents one in another - remarkably not unlike Phantom's goals. The trouble is, they did these in document interchange formats! Office succeeded, and the insane complexity of reverse-engineering its formats actually became a great business "moat". But decades later, after switching the surface structure from binary insanity to XML, it still contains attributes like `autoSpaceLikeWord95` and `footnoteLayoutLikeWW8` :-( http://www.robweir.com/blog/2007/01/how-to-hire-guillaume-portes.html http://www.robweir.com/blog/2007/01/how-to-hire-guillaume-po... A lot has been written assuming malice in OOXML, but you can also argue it'd require unbelievable competence to evolve their codebase to anything other than this! If you never needed pervasive dump/load abstractions, your formats map to 1:1 to your semantics, and the only way to evolve is keeping old semantics around, forever... EDIT: I can't help copy pasting more from the last link: - lineWrapLikeWord6 (Emulate Word 6.0 Line Wrapping for East Asian Text) - mwSmallCaps (Emulate Word 5.x for Macintosh Small Caps Formatting) - shapeLayoutLikeWW8 (Emulate Word 97 Text Wrapping Around Floating Objects) - truncateFontHeightsLikeWP6 (Emulate WordPerfect 6.x Font Height Calculation) - useWord2002TableStyleRules (Emulate Word 2002 Table Style Rules) - useWord97LineBreakRules (Emulate Word 97 East Asian Line Breaking) - wpJustification (Emulate WordPerfect 6.x Paragraph Justification) - shapeLayoutLikeWW8 (Emulate Word 97 Text Wrapping Around Floating Objects)