TeX provides groups as a means to restrict the visibility
of registers. This construction is well known in the TeX world but does
not coincide with the groups as known from other programming languages. If we
refrain from storing the register value in a global array we can come to the
alternate solution of storing it in the control sequence used to access it.
With this variant we can provide a means to define an arbitrary number of
registers which follow the same scoping rules ike the variables in
Pascal-like languages.
εχTeX is a reimplementation of TeX in Java. It is developed with the extensibility and configurability in mind. The idea of an alternative storage for registers can be implemented in εχTeX as an extension. It is shown which steps are required for such an implementation. In this course the extensibility of εχTeX is demonstrated.
