signal line

基本解釋

Those buttons usually have lamps and can provide features such as call holding, line status, signaling, conferencing and intercom.
這些鍵有指示燈竝且可以提供諸如電話接聽等待、線路狀態(tài)、信令、會(huì)議和連絡(luò)用對(duì)講電話裝置的功能。
wiki.mycreative.com.cn
Considering the signaling system project for Beijing subway Line 4 and its extension, two different implementation options are discussed.
針對(duì)北京地鉄4號(hào)線及其延伸，討論線路延伸工程中信號(hào)系統(tǒng)適用的兩種實(shí)施方案。
Signaling the line of books that are waiting to be read, it isn't rare to hear him say "Dear God, I'm an imposter, when will people realise I can't read all this?"
他也會(huì)劃線標(biāo)記出書中待讀的部分，經(jīng)常就會(huì)聽到他說“天啊，我就像個(gè)江湖騙子，人們什麼時(shí)候才會(huì)知道我還有這麼多書需要讀啊？”

If you start to cross the line without signaling, it triggers a warning.
FORBES: Cadillac Has A Backseat Driver I Can Live With
The relative performance broke its downtrend, line c, in May signaling the resumption of the major uptrend.
FORBES: Don't Bet Against the Consumer
The RS broke its major downtrend, line a, in April, signaling its market-leading performance in the second quarter.
FORBES: 4 Surviving Sectors