On the page:

https://docs.python.org/3.10/library/sys.html#sys.prefix

the text says

The main collection of Python library modules is installed in the directory prefix/lib/pythonX.Y while the platform independent header files (all except pyconfig.h) are stored in prefix/include/pythonX.Y, where X.Y is the version number of Python, for example 3.2.

However, this seems to only be true on *nix systems. On Windows, the lib and header files are just in prefix/lib and prefix/include. Maybe the text should be changed to say:

On linux, the main collection of Python library modules is installed in the directory prefix/lib/pythonX.Y while the platform independent header files (all except pyconfig.h) are stored in prefix/include/pythonX.Y, where X.Y is the version number of Python, for example 3.2. On Winodws, there are in prefix/lib and prefix/includes.

On Windows, I believe the correct sentence would be "On Windows, they are in prefix/Lib and prefix/include".  Ned, how to complete "On macOS, they are in ?."

Victor, with recent file movement, is "while the platform independent header files (all except pyconfig.h) are stored in prefix/include" still true?  In what way is pyconfig.h exceptional?  Should 'include' be augmented with 'or its subdirectories'?

Which installations paths are used varies on other factors besides platform. Rather than duplicate information here, I suggest simplifying the sys.prefix doc here by removing the details about installation paths and instead refer to the Installation Paths section of the sysconfig module documentation, which should be the primary reference for this info:

https://docs.python.org/3/library/sysconfig.html#installation-paths

> Victor, with recent file movement, is "while the platform independent header files (all except pyconfig.h) are stored in prefix/include" still true?

Are you talking about Include/cpython/ and Include/internal/ subdirectories?

> Should 'include' be augmented with 'or its subdirectories'?

You can add it if you want.

Ned, I like your idea.  In particular, link to sysconfig.get_paths for how prefix is used on a particular machine to define installation paths.

Sidenote:
https://docs.python.org/3/library/sysconfig.html#installation-paths
says "Python currently supports seven schemes:" and lists 5  get_scheme_names list 6, with the extra one being
'osx_framework_user'.  Would
  osx_framework_user: scheme for macOS
be a satisfactory entry?

Hey thanks Ned, sysconfig was exactly what I was looking for when I was reading the sys documentation.

> Would osx_framework_user scheme for macOS be a satisfactory entry?

Yes, it should be there.

New changeset 4575c01b750cd26377e803247c38d65dad15e26a by Terry Jan Reedy in branch 'main':
bpo-45788: Link sys.prefix doc to 'Installation paths' (#29606)
https://github.com/python/cpython/commit/4575c01b750cd26377e803247c38d65dad15e26a

New changeset c06c7c489a82b2db023bb947f0c4d21ad93b8308 by Miss Islington (bot) in branch '3.9':
[3.9] bpo-45788: Link sys.prefix doc to 'Installation paths' (GH-29606) (GH-29632)
https://github.com/python/cpython/commit/c06c7c489a82b2db023bb947f0c4d21ad93b8308

New changeset 2a630e716e488ac420d308736568829f76e388a3 by Miss Islington (bot) in branch '3.10':
[3.10] bpo-45788: Link sys.prefix doc to 'Installation paths' (GH-29606)
https://github.com/python/cpython/commit/2a630e716e488ac420d308736568829f76e388a3