Short answer: version 31 .vce files. The longer answer explains
why that qualifier matters, because two files with the same extension are not necessarily
the same format.
The .vce container carries a version number, and more than one version is in
use. Files with the same extension can differ internally, which is why a reader can handle
one file and reject the next.
FreeVCE has been verified against version 31 — that is the version of every exam file this project has been able to test with, question by question. Later versions of the format exist. They are not supported, because no example of one has been available to build against and verify.
Both are extensions you will see in the same context as .vce. Neither has
been examined by this project, so there is nothing to tell you about their structure that
would not be guesswork. Neither is supported.
The import reports the failure rather than silently producing nothing. That result is useful here: support for a format version can only be written against a real example of it, which is what the collection described below exists to gather.
FreeVCE opens .vce files in a browser tab. There is
nothing to install and no account to create. Exams, answers and progress are stored in the
browser's own database on your device, and once the page has loaded once it works with no
network at all. It contains no exam content — you open files you already have.