There is one exception to the requirement to explicitly configure a key block range before a system is first started. This is that it is possible to have a single system in a system landscape that does not have a key block range explicitly configured before it is first started. This is because if no key block range is explicitly configured, a default key block range of group 3, range 2 is used. Therefore, it is possible to have a single system in a landscape which is not explicitly configured with a key block range before it is first started, as it will use the default key block range allocation group 3, range 2.
However, every other system in the system landscape will need to have a key block range explicitly configured, and no other systems can be configured with the key block range group 3, range 2.
Note that the reason for supporting a default key block range allocation is to facilitate the enabling of CTM on a production system after a technical upgrade. Please refer to section 5.4 - Enabling use of CTM on an existing application installation for further information.