W = weight per unit length (lb/ft or kg/meter for metric )

A = cross sectional area (in^2 or cm^2 for metric)

Ix = moment of inertia about the x (horizontal/strong) axis (in^4 or cm^4 for metric)
Iy = moment of inertia about the y (vertical/weak) axis (in^4 or cm^4 for metric)
http://en.wikipedia.org/wiki/Second_moment_of_area

Sx = Section Modulus about the x axis (in^3 or cm^3 for metric)
Sy = Section Modulus about the y axis (in^3 or cm^3 for metric)
http://en.wikipedia.org/wiki/Section_modulus

 Note: At this time, only the weight property is used by [[Bentley Structural]].  The rest of the properties are loaded into memory but never used.  The use of the weight property is limited to the calculation of the total weight of the member (= weight/unit length X length) in the Structural Quantity Report Spreadsheet.