clarification for pg_basebackup and major versions

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/18/app-pgbasebackup.html
Description:

Hi, Team !

Could we pls. clarify the following statement on the documentation page
https://www.postgresql.org/docs/18/app-pgbasebackup.html:
'pg_basebackup works with servers of the same or older major version, down
to 9.1.'

What does it exactly mean 'works with servers of the same or older major
version' ?

Most probably it means the possibility to use pg_basebackup binary of
version PG 17 to take backup of PG 14 server. Or something else ?

But it's definitely not ability to use pg_basebackup for PostgreSQL major
version upgrade, since pg_basebackup is not listed among the supported
options in https://www.postgresql.org/docs/18/upgrading.html

So, pls. let me propose two things:
- to clarify how pg_basebackup works with servers of the same or older major
version
- to clearly specify pg_basebackup cannot be used for PostgreSQL major
version upgrade

It could be done on the same page
https://www.postgresql.org/docs/18/app-pgbasebackup.html

Thanks !

best regards
Alexey Shishkin