Compound Variable Names
name may be "compound" in that it may be composed of
several parts (separated by periods) some of which may have
variable values. The parts are then substituted independently,
to generate a fully resolved name. In general,
s0.s1.s2.---.sn is substituted to form
d0.v1.v2.---.vn where d0 is uppercase of s0, and
v1-vn are values of s1-sn
This facility may be used for traditional arrays,
content-addressable arrays, and other indirect addressing
modes. As an example, the sequence:
J = 5; a.j = "fred";
would assign fred to the variable A.5.
The stem of name (i.e. that part up to and including the
first ".") may be specified on the DROP and PROCEDURE
EXPOSE instructions and affect all variables starting with
that stem. An assignment to a stem assigns the new value to
all possible variables with that stem.