Senses
暗线/ 暗線 hidden clue
A secret or hidden story thread in a literary work that is not directly described but is shown indirectly.
暗线/ 暗線 undercover agent
A person working secretly as an informant or internal contact for one's own side.
暗线/ 暗線 dark line
A dark absorption line in a spectrum
暗线/ 暗線 hidden wiring
Electrical wiring or cables installed inside a wall or under a floor