A jump via an indirect address, i.e. the
jump instruction contains the address of a memory location
that contains the address of the next instruction to execute.
The location containing the address to jump to is sometimes
called a vector.
Indirect jumps make normal code hard to understand because the
jump target is a run-time property of the program that depends
on the execution history. They are useful for, e.g. allowing
user code to replace operating system code or setting up