What does it mean when psql has blank database access privileges?

Question

When I run \l+ in psql to get a list of all databases and their access privileges, I see that some of the databases have blank access privileges. What does it mean when the Access privileges column is blank in psql?

If there is some sort of default, how can I see what that default is?

me=# \l+
                                                                      List of databases
    Name     |    Owner    | Encoding |   Collate   |    Ctype    |   Access privileges   |  Size   | Tablespace |                Description                 
-------------+-------------+----------+-------------+-------------+-----------------------+---------+------------+--------------------------------------------
 me          | me          | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                       | 7239 kB | pg_default | 
 postgres    | postgres    | UTF8     | en_US.UTF-8 | en_US.UTF-8 |                       | 7151 kB | pg_default | default administrative connection database
 template0   | postgres    | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +| 7041 kB | pg_default | unmodifiable empty database
             |             |          |             |             | postgres=CTc/postgres |         |            | 
 template1   | postgres    | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +| 7041 kB | pg_default | default template for new databases
             |             |          |             |             | postgres=CTc/postgres |         |            | 
(4 rows)

Answer 1

What does it mean when the Access privileges column is blank

Quote from the manual:

If the "Access privileges" column is empty for a given object, it means the object has default privileges (that is, its privileges column is null). Default privileges always include all privileges for the owner, and can include some privileges for PUBLIC depending on the object type, as explained above

The default privileges are also documented there

PostgreSQL grants privileges on some types of objects to PUBLIC by default when the objects are created. No privileges are granted to PUBLIC by default on tables, table columns, sequences, foreign data wrappers, foreign servers, large objects, schemas, or tablespaces. For other types of objects, the default privileges granted to PUBLIC are as follows: CONNECT and TEMPORARY (create temporary tables) privileges for databases; EXECUTE privilege for functions and procedures; and USAGE privilege for languages and data types (including domains).