Cross-link open-source guidance and API guidelines
PiperOrigin-RevId: 419823271
Change-Id: If54a601f2d6742bb053531fc01ca4aeb7ccfbd17
diff --git a/docs/open_source.md b/docs/open_source.md
index b5504f0..845448b 100644
--- a/docs/open_source.md
+++ b/docs/open_source.md
@@ -23,13 +23,18 @@
### Exceptions
-The only exception to this definition is the Android platform SDK, which does
-not release sources until well after its API surface has been finalized.
+The only unconditional exception to this definition is the Android platform SDK,
+which does not release sources until well after its API surface has been
+finalized.
Libraries which are developed against the pre-release Android platform SDK _may_
remain closed-source until the platform SDK's API surface is finalized, at which
they **must** move to open-source.
+In specific cases, libraries *may* include closed-source dependencies. See the
+[Open-source compatibility](api_guidelines.md#dependencies-aosp) section of the
+API Guidelines for implementation details.
+
### Examples of products that are _not_ open-source
* A bundled `.so` file with no publicly-available source code
