REDUCE is by default case insensitive, and depending on the installation the default behaviour may be to map upper case characters to lower case, or the reverse. This insensitivity is primarily to allow for greater portability of the REDUCE code, it is however, somewhat undesirable for a mathematical system, since the same symbol in different case is often used to represent different quantities.
By default, REDTEN is a case-sensitive system: it clears the
control switches raise and lower
at startup (these switches can be
set by the user with the commands on or off
). In an upper-case system the
raise switch is on, while the lower switch is off, the
reverse may be true in lower-case systems, but the exact combination
is implementation dependent.
Improperly setting these switches can
trap the user in the system, with no way to gracefully exit or reset
the switches (the REDUCE quote character ``!'' can be used to
inhibit the case-mapping of the system, see below).
If the REDUCE system is upper-case by default, a package to map the
names of many of the commonly used operators and functions to lower
case is available (see §7.4); this is not needed if the system is
by default lower-case. In this document it is assumed that the
REDUCE system is lower-case.