There is a subtle bug while installing system. One of the steps is activation
of repositories during installation. See:
https://doc.opensuse.org/documentation/leap/startup/html/book-startup/cha-install.html#sec-yast-install-online-repos

Depending if you enable online repositories (not repositories itself, just
enable this stage) the final system will have different list than when you
don't enable them during installation.

In first case you will get SLE repos listed, in the second case they will be
not included (at all). 

I added the list of repos provided with online repositories (_stage_) not
enabled -- SLE one are missing.

Of course user can add them manually, but it is a surprise effect, because
sometime later user won't be able to install some package because of the broken
dependency coming from SLE repo.


#  | Alias                     | Name                               | Enabled |
GPG Check | Refresh | URI
---+---------------------------+------------------------------------+---------+-----------+---------+------------------------------------------------------------------------
 1 | openSUSE-Leap-15.3-1      | openSUSE-Leap-15.3-1               | No      |
----      | ----    | cd:/?devices=/dev/disk/by-id/ata-VBOX_CD-ROM_VB2-01700376
 2 | repo-debug                | Debug Repository                   | No      |
----      | ----    |
http://download.opensuse.org/debug/distribution/leap/15.3/repo/oss/
 3 | repo-debug-non-oss        | Debug Repository (Non-OSS)         | No      |
----      | ----    |
http://download.opensuse.org/debug/distribution/leap/15.3/repo/non-oss/
 4 | repo-debug-update         | Update Repository (Debug)          | No      |
----      | ----    | http://download.opensuse.org/debug/update/leap/15.3/oss/
 5 | repo-debug-update-non-oss | Update Repository (Debug, Non-OSS) | No      |
----      | ----    |
http://download.opensuse.org/debug/update/leap/15.3/non-oss/
 6 | repo-non-oss              | Non-OSS Repository                 | Yes     |
(r ) Yes  | Yes     |
http://download.opensuse.org/distribution/leap/15.3/repo/non-oss/
 7 | repo-oss                  | Main Repository                    | Yes     |
(r ) Yes  | Yes     |
http://download.opensuse.org/distribution/leap/15.3/repo/oss/
 8 | repo-source               | Source Repository                  | No      |
----      | ----    |
http://download.opensuse.org/source/distribution/leap/15.3/repo/oss/
 9 | repo-update               | Main Update Repository             | Yes     |
(r ) Yes  | Yes     | http://download.opensuse.org/update/leap/15.3/oss/
10 | repo-update-non-oss       | Update Repository (Non-Oss)        | Yes     |
(r ) Yes  | Yes     | http://download.opensuse.org/update/leap/15.3/non-oss/