Fractional Factorial Design Objects

DESCRIPTION:
Tests for objects of class "fac.design". Primarily designed for use with Subscript.

USAGE:
is.fac.design(x)

REQUIRED ARGUMENTS:
x:
an S-PLUS object.

VALUE:
is.fac.design tests whether x is a fac.design object. That is, it returns TRUE if x satisfies a condition for fac.design and FALSE otherwise.

NOTE:
The testing is not exhaustive, and does not guarantee that x satisfies all of the properties (loosely) required of a fac.design object.