permanent snow

permanent snow cover

single line permanent ground (SLG) fault

climatic snow line

climatic snow-line

local snow line

orographic snow line

perpetual snow line

snow line

snow line altitude

Snow line rising

snow-line

Double line-line voltage control

line-line extreme distance

line-line topological relation in traffic network

on-line line loss

loss-free line (=lossless line =lossless transmission line)

SDSL Single-Line Digital Subscriber Line，Single-Line DSL

Heavy snow and snow -storm