Standard can also be a ubiquitous implementation: OOXML, PDF, CUDA, Linux, glibc, pulseaudo, ffmpeg, imagemagick, tensorflow, systemd, Windows, MySQL, React, Java, QT, Electron.

Since standards bodies these days are really documentation effots it seems silly to say that implementation defined standards aren't. It's practically where any 'proper' standard comes from these days where the market leader is essentially the reference implementation.