denotes subtraction or unary minus or negative concatenation for
strings.
denotes multiplication.
denotes division.
^
denotes exponentiation.
denotes exponentiation (same as ^ ).
vflc:==
functionsymbolrealintegerstring
deals with the fact that the data types of the operations and operands
have to match; otherwise an error message is issued.
The available functions, such as SIN, COS, and TAN, are defined
in Section 2.16.