英语专业术语不懂，求指教

7.ews-5 "bands"-perforated metal panel cladding system a.??system description : vertical, under -slung and back-tilted panelized perforated metal panel system forming faceted bands around the building. system consists of an outer layer of custom perforated and solid metal panels supported on a unitized aluminum sub-frame assembly designed to connect to the primary building structure to accommodate cumulative structural movements without pronounced differential effect.refer to section 074213 for detailed specifications. 1) the fastening methodology must minimize the visibility of the seams in accordance with the engineering intent. 2) the custom framing allows for differential building movement 3??the framing is attached to an overall panel substructure comprised of factory -constructed aluminum members sized accordingly 4) the system is supported on a band facet superstructure to be coordinated with structural engineer 5) the system is coordinated with facade illumination requirements to be determined b.system materials: 1) perforated stainless steel panels -10 gauge (3.5mm) thick type 316l stainless steel panel with custom perforations, 50mm return legs with back face v-cut release. 2) aluminum support/backup frame - alloy 6063-t6,pvdf2 coated. 3) steel bracket receivers - painted mild steel elements (to be determined) pre- welded to primary structure backup. 客户要冲孔网，以上是产品要求。只是这句不懂：50mm return legs with back face v-cut release. 这是客户第二封信： please confirm on the following items as well. 1.) is directional satin finish no. 4 considered in your proposal? 2.) is fabrication and 50mm return legs on the edge included? 也看不懂什么意思。不敢贸然回复客户，急等帮助中。。。。。。。。。。。。。。。。。。。。。。 在此谢过各位！！！！ :)