the part of the simple expressio'l that precedes the operator, and the term that immediately follows he operator. The two operands of a relational operator are the simple 1'.\ pressions that immediately precede and follow the operator. The opel ;tnd of a sign in a simple expression is the term that immediately follov ~ the sign. The operand of not in a factor is the factor following not 

The order of evaluation 01 the operands of an operator is implementation-dependent. A Sl ill1dard program must not make any assumption about this order. The I,' It operand might be evaluated before or after the right operand, or they III ight be evaluated in parallel. In fact, sometimes one operand might not 'Ie evaluated at all for some values of the other operand. For example, I'valuating the expression (j * (i di v j)) when j is zero mighl vidd zero on one implementation, where on another implementati( 'II It might be an error due to the division by zero. 

The type of a factor is derived I to III the type of its constituent (e.g., variable or function). Ifthe const 11ucnt's type is a subrange, then the type of the factor is the host type 111" the subrange; if the constituent's type is a set type with a subrange .. IS its base type, then the type of the factor is a set type with the host type of that subrange type as its base type; otherwise, the type of the f;lCtor is the same as the type of the constituent. 

The symbol nil possesses every pointer type and represents the nil value. 

A set constructor denotes a ~et value. If there are no element descriptions in the set constructor, 1 hen it denotes the empty set that is a value of every set type. Otherwisl, the elements of the set value are described by the element descriptions in the set constructor. All expressions in the element descripl H)JlS of a set constructor must have the same type, which is the base tYlle (If the type of the set constructor. The type of a set constructor is tpth packed and unpacked, and is compatible with any other set type I hat has a compatible base type. 

An element description consistlllg of a single expression describes the element that has the value den(lled hy the expression. An element description of the form a .. b dest ribes an element for each value x that satisfies a <= x <= b. If a > '. then a .. b denotes no elements. The order of evaluation of the expre~i.;ions in an element description and 

