CURTAIN WALL – A thin wall, supported by the structural steel or concrete frame of the building independent of the wall below. Also a metal (most often aluminum) framing system on the face of a building containing vision glass panels and spandrel panels made of glass, aluminum, or other material.
http://www.proofrock.com/glossary.html

[0012]FIG. 1 is a typical front elevation view of the curtain wall mullion frame of the present invention with horizontal and vertical mullions;
[0013]FIG. 2 is a side cross-section view of the curtain wall of the present invention showing various details;
:
[0035] The frame 1 is required to be properly supported and anchored to the building on which the curtain wall is built, to help transfer the lateral loads from the walls to the building. For example, the frame 1 can be mounted and supported by upper and lower building structures, 29 and 30, respectively, which can be made of concrete, wood, metal or other building material.
http://www.google.com/patents/US20020144476
Fig.1: http://patentimages.storage.googleapis.com/US20020144476A1/U...
Fig 2: http://patentimages.storage.googleapis.com/US20020144476A1/U...
Demnach handelt es sich um einen Rahmen oder Gerüst mit eingefassten Glasscheiben.

„Smooth“ bedeutet nicht nur glatt, sondern auch
smooth {adj} nahtlos [Übergang]
tech. smooth {adj} [e.g. movement, motion] ruckfrei [z. B. Bewegung,, Lauf]
smooth {adj} [whiskey] weich
:
smooth {adj} fugenlos [fig.] [Übergang]
http://www.dict.cc/?s=smooth

auch “cross-section” ist mehrdeutig:
tech. cross-section {adj} Kahneisen-® [z. B. Profil]
cross section Kreuzschnitt {m}
cross section Profil {n} [Querschnitt]
cross section Querschnitt {m}
http://www.dict.cc/?s=cross-section

Hier scheint es auf die Fugenlosigkeit und der glatten Übergänge des Profils anzukommen.