IEC 61156-4 Ed. 2.0 b:2003

Covers individually unscreened 20 pairs/10 quads or more for vertical shafts or vertically between floors. When installed vertically extra length requirements may be applicable and are defined in the appropriate specifications. The cables may be provided with a common screen over the cable core. These cables are suitable for the various communication systems for which the reference is given in the appropriate detail specification.