2.1.48 [ECMA-262-1999] Section 15.1.2.1, eval(x)

V0082:

If value of the eval property is used in any way other than a direct call (that is, other than by the explicit use of its name as an Identifier which is the MemberExpression in a CallExpression), or if the eval property is assigned to, an EvalError exception may be thrown.

JScript 5.x does not restrict usage of the function that is the initial value of the eval property or restrict assignment to the eval property. It does not throw EvalError in the situations.