witness mark
n.— «Stanley Bostitch has developed a fixing gun designed for both industrial and construction applications. Its 23 Gauge Headless Pinner boasts a magazine that needs no adjustment for varying pin lengths and gives a clean finish clear of witness marks.» —“In Stock” Construction News Jan. 13, 2005. (source: Double-Tongued Dictionary)
Further reading
Understanding the varieties of conversational styles can mean the difference between feeling you’re understood and being insulted. “High-involvement” speakers interrupt or talk along with someone else to signal their enthusiasm...
In an article in The Atlantic magazine, humorist Mark Twain quoted a sing-songy bit of doggerel about conductors punching railroad fares that illustrates how colored paper has long been used to encode information. This is part of a complete episode...