> It's apache2.0, so by definition it's open source.
That's not true by any of the open source definitions in common use.
Source code (and, optionally, derived binaries) under the Apache 2.0 license are open source.
But compiled binaries (without access to source) under the Apache 2.0 license are not open source, even though the license does give you some rights over what you can do with the binaries.
Normally the question doesn't come up, because it's so unusual, strange and contradictory to ship closed-source binaries with an open source license. Descriptions of which licenses qualify as open source licenses assume the context that of course you have the source or could get it, and it's a question of what you're allowed to do with it.
The distinction is more obvious if you ask the same question about other open source licenses such as GPL or MPL. A compiled binary (without access to source) shipped with a GPL license is not by any stretch open source. Not only is it not in the "preferred form for editing" as the license requires, it's not even permitted for someone who receives the file to give it to someone else and comply with the license. If someone who receives the file can't give it to anyone else (legally), then it's obvioiusly not open source.
"Compiled binaries" are just meant to be an example. For the purpose of whether something is open source, it doesn't matter whether something is a "binary" or something completely different.
What matters (for all common definitions of open source): Are the files in "source form" (which has a definition), or are they "derived works" of the source form?
Going back to Apache 2.0. Although that doesn't define "open source", it provides legal definitions of source and non-source, which are similar to the definitions used in other open source licenses.
As you can see below, for Apache 2.0 it doesn't matter whether something is a "binary", "weights" or something else. What matters is whether it's the "preferred form for making modifications" or a "form resulting from mechanical transformation or translation". My highlights are capitalized:
- Apache License Version 2.0, January 2004
- 1. Definitions:
- "Source" form shall mean the PREFERRED FORM FOR MAKING MODIFICATIONS, including BUT NOT LIMITED TO software source code, documentation source, and configuration files.
- "Object" form shall mean any form resulting from MECHANICAL TRANSFORMATION OR TRANSLATION of a Source form, including BUT NOT LIMITED TO compiled object code, generated documentation, and conversions to other media types.
> "Source" form shall mean the PREFERRED FORM FOR MAKING MODIFICATIONS, including BUT NOT LIMITED TO software source code, documentation source, and configuration files.
Yes, weights are the PREFFERED FORM FOR MAKING MODIFICATIONS!!! You, the labs, and anyone sane modifies the weights via post-training. This is the point. The labs don't re-train every time they want to change the model. They finetune. You can do that as well, with the same tools/concepts, AND YOU ARE ALLOWED TO DO THAT by the license. And redistribute. And all the other stuff.
That's not true by any of the open source definitions in common use.
Source code (and, optionally, derived binaries) under the Apache 2.0 license are open source.
But compiled binaries (without access to source) under the Apache 2.0 license are not open source, even though the license does give you some rights over what you can do with the binaries.
Normally the question doesn't come up, because it's so unusual, strange and contradictory to ship closed-source binaries with an open source license. Descriptions of which licenses qualify as open source licenses assume the context that of course you have the source or could get it, and it's a question of what you're allowed to do with it.
The distinction is more obvious if you ask the same question about other open source licenses such as GPL or MPL. A compiled binary (without access to source) shipped with a GPL license is not by any stretch open source. Not only is it not in the "preferred form for editing" as the license requires, it's not even permitted for someone who receives the file to give it to someone else and comply with the license. If someone who receives the file can't give it to anyone else (legally), then it's obvioiusly not open source.