NEP: Add "Provisional" status and move nep 18 to provisional

4 files changed, 28 insertions, 3 deletions

diff --git a/doc/neps/_static/nep-0000.png b/doc/neps/_static/nep-0000.png
index 51eb2b258..0fc8176d2 100644
--- a/doc/neps/_static/nep-0000.png
+++ b/doc/neps/_static/nep-0000.png
diff --git a/doc/neps/index.rst.tmpl b/doc/neps/index.rst.tmpl
index 1230d8077..0ad8e0f80 100644
--- a/doc/neps/index.rst.tmpl
+++ b/doc/neps/index.rst.tmpl
@@ -29,8 +29,19 @@ Meta-NEPs (NEPs about NEPs or Processes)
 
    nep-template
 
-Accepted NEPs, implementation in progress
------------------------------------------
+Provisional NEPs (provisionally accepted; interface may change)
+---------------------------------------------------------------
+
+.. toctree::
+   :maxdepth: 1
+
+{% for nep, tags in neps.items() if tags['Status'] == 'Provisional' %}
+   {{ tags['Title'] }} <{{ tags['Filename'] }}>
+{% endfor %}
+
+
+Accepted NEPs (implementation in progress)
+------------------------------------------
 
 .. toctree::
    :maxdepth: 1
diff --git a/doc/neps/nep-0000.rst b/doc/neps/nep-0000.rst
index 5e719b0f9..89ba177cb 100644
--- a/doc/neps/nep-0000.rst
+++ b/doc/neps/nep-0000.rst
@@ -111,6 +111,20 @@ Once a NEP has been ``Accepted``, the reference implementation must be
 completed.  When the reference implementation is complete and incorporated
 into the main source code repository, the status will be changed to ``Final``.
 
+To allow gathering of additional design and interface feedback before
+committing to long term stability for a language feature or standard library
+API, a NEP may also be marked as "Provisional". This is short for
+"Provisionally Accepted", and indicates that the proposal has been accepted for
+inclusion in the reference implementation, but additional user feedback is
+needed before the full design can be considered "Final". Unlike regular
+accepted NEPs, provisionally accepted NEPs may still be Rejected or Withdrawn
+even after the related changes have been included in a Python release.
+
+Wherever possible, it is considered preferable to reduce the scope of a
+proposal to avoid the need to rely on the "Provisional" status (e.g. by
+deferring some features to later NEPs), as this status can lead to version
+compatibility challenges in the wider NumPy ecosystem.
+
 A NEP can also be assigned status ``Deferred``.  The NEP author or a
 core developer can assign the NEP this status when no progress is being made
 on the NEP.
diff --git a/doc/neps/nep-0018-array-function-protocol.rst b/doc/neps/nep-0018-array-function-protocol.rst
index 4e0fee384..75f4132a4 100644
--- a/doc/neps/nep-0018-array-function-protocol.rst
+++ b/doc/neps/nep-0018-array-function-protocol.rst
@@ -7,7 +7,7 @@ NEP 18 — A dispatch mechanism for NumPy's high level array functions
 :Author: Marten van Kerkwijk <mhvk@astro.utoronto.ca>
 :Author: Hameer Abbasi <hameerabbasi@yahoo.com>
 :Author: Eric Wieser <wieser.eric@gmail.com>
-:Status: Accepted
+:Status: Provisional
 :Type: Standards Track
 :Created: 2018-05-29
 :Resolution: https://mail.python.org/pipermail/numpy-discussion/2018-August/078493.html