safety sense).  This could
cause security or interop failures.

Instead, we suggest that potential users of that API consider:

- whether their use can fit in standard extensions such as ALPN,
  or [ALPS][alps][^3].
- if not, whether they can fit in a more general extension, and define
  and standardize that in the [IETF TLSWG][tlswg].

Note the above is not a guarantee or offer that rustls will implement
any specific extensions that are standardized by the IETF TLSWG.
It is a non-goal of this project to implement absolutely everything.

For experimentation and pre-standardization testing, we suggest
forking rustls.

See also: [Go's position on such an API][golang].

[alps]: https://datatracker.ietf.org/doc/html/draft-vvv-tls-alps
[golang]: https://github.com/golang/go/issues/51497
[tlswg]: https://datatracker.ietf.org/wg/tls/charter/
[^3]: rustls does not currently implement ALPS, but it is something we
  would consider once standardised and deployed.