/ SV - 4 b ▁Systems / Services ▁Function ality ▁Description ▁ ▁The ▁SV - 4 a ▁documents ▁system ▁functional ▁hier arch ies ▁and ▁system ▁functions , ▁and ▁the ▁system ▁data ▁flows ▁between ▁them . ▁The ▁SV - 4 ▁from ▁Do D AF ▁v 1 . 0 ▁is ▁designated ▁as ▁' SV - 4 a ' ▁in ▁Do D AF ▁v 1 . 5 . ▁Although ▁there ▁is ▁a ▁correlation ▁between ▁O V - 5 ▁or ▁business - process ▁hier arch ies ▁and ▁the ▁system ▁functional ▁hierarchy ▁of ▁SV - 4 a , ▁it ▁need ▁not ▁be ▁a ▁one - to - one ▁mapping , ▁hence , ▁the ▁need ▁for ▁the ▁Oper ational ▁Activity ▁to ▁Systems ▁Function ▁Trace ability ▁Matrix ▁( SV - 5 a ), ▁which ▁provides ▁that ▁mapping . ▁ ▁SV - 5 a , ▁SV - 5 b , ▁SV - 5 c ▁Oper ational ▁Activity ▁to ▁Systems ▁Function , ▁Oper ational ▁Activity ▁to ▁Systems ▁and ▁Services ▁Trace ability ▁Mat rices ▁ ▁Oper ational ▁Activity ▁to ▁SV - 5 a ▁and ▁SV - 5 b ▁is ▁a ▁specification ▁of ▁the ▁relationships ▁between ▁the ▁set ▁of ▁oper ational ▁activities ▁applicable ▁to ▁an ▁architecture ▁and ▁the ▁set ▁of ▁system ▁functions ▁applicable ▁to ▁that ▁architecture . ▁The ▁SV - 5 ▁and ▁extension ▁to ▁the ▁SV - 5 ▁from ▁Do D AF ▁v 1 . 0 ▁is ▁designated ▁as ▁' SV - 5 a ' ▁and ▁‘ SV - 5 b ’ ▁in ▁Do D AF ▁v 1 . 5 ▁respectively . ▁ ▁SV