They did try to standardise the test formats, but the big companies (who didn't actually want interoperability) just turned it into a big XML snowjob, subverting the standardising groups in a similar way to Microsoft's OOXML debacle.
There is some interoperability, mostly because the open systems like Moodle reverse-engineer stuff. I believe some of the systems now encrypt their output to prevent this, which is absolutely shocking to me, but typical of big corporate software which is what these big players are.
There is some interoperability, mostly because the open systems like Moodle reverse-engineer stuff. I believe some of the systems now encrypt their output to prevent this, which is absolutely shocking to me, but typical of big corporate software which is what these big players are.