To Update to a newer ILIAS- version it is necessary to change the branch of the svn repository befor update. The basic syntax is
 
svn switch name_of_new_branch
 
as an example for the update to the ilias 4.3 branch use the commands

svn switch https://svn.ilias.de/svn/ilias/branches/Release_4_3_x_branch
svn up

Before the branch- switch it is advisable to update the system and database to the current release of the branch as described in the update procedure, and don't forget about the skin settings
After that remember to update the database and language
 
If the new branch introduces new objects, permissions and role templates need to be modified to make the new objects available to the users.
The basic procedure is:

• In Administration- Roles filter the role-templates and give Permissions to use new objects to all intended roles
• modify global roles according to your needs
• copy the role templates to those roles that had been created using the templates

In our installation we have used some special changes. The usual Header Icon was replaces by our company logo, this is found in the file HeaderIcon.png in the skin and template- folder. An update may overwrite this file, so it must be replaced after the update.