A . (A)输气干线、增压站、输配气站、清管站及防腐站;
B . (B)集配气管线、输气干线、配气站、清管站;
C . (C)矿场集配气管网、天然气增压站及净化厂、输配气站、清管站及防腐站;
D . (D)集配气管线及输气干线、天然气增压站及天然气净化处理厂、集输配气站场、清管站及防腐站