|Description: Extend class notation to
include unary minus. The symbol is not a
class by itself but part of a compound class definition. We do this
rather than making it a formal function since it is so commonly used.
Note: We use different symbols for unary minus () and subtraction
cmin 6959 () to prevent syntax ambiguity. For example, looking at the
syntax definition co 5455, if we used the same symbol
then " " could
mean either "
it could represent the (meaningless) operation of
" and "
with "operation" "".
On the other hand, "
" is unambiguous.|