Default order of select datname from pg_database

Hi all,

By any change, does the following query have an "order by" by default when
omitted?:

select datname from pg_database;

I know you could pass and ORDER BY datname or similar but what I don't know
is if by default there's some kind of sort when the order by is omitted.

I executed that query against one of my servers and while looking at the
names it seems complety random, the order is always the same, for instance:

web2
template0
asdf
basic
postgres
web3
.....

Does anybody know?

Thanks in advance!

--
Elías David.