Q. According to CMOS 6.86, “The en dash can be used in place of a hyphen in a compound adjective when one of its elements consists of an open compound.” And according to 5.96, “If a compound noun is an element of a phrasal adjective, the entire compound noun must be hyphenated to clarify the relationship among the words,” as in the example “time-clock-punching employees.” But “time clock” is an open compound, so this seems contradictory. Am I misunderstanding something?
A. Those two paragraphs do seem to contradict each other, but it’s important to note that CMOS would recommend reworking the phrase “time clock–punching employees,” if possible, to avoid the need for an en dash. The problem is that more than a few readers will assume that the en dash is simply a kind of hyphen (if they notice the difference at all), which could result in a misreading, at least initially, of “clock-punching employees” who are somehow modified by “time.”
A phrase like “Civil War–era veterans,” by contrast, is a little easier to parse, thanks to the initial caps, which can help readers to understand that “Civil War” is a single term joined to the word “era.” The lowercase term “time clock,” though it’s common enough, doesn’t stand out in the same way. That’s why “country music–influenced lyrics” (the analogous example in CMOS 6.86) is followed by an alternative: “lyrics influenced by country music.”
We could have offered a second alternative: “country-music-influenced lyrics” (with two hyphens). But the noun phrase “country music” doesn’t seem to need a hyphen even when it’s used attributively before another noun, as in “country music lyrics,” which rarely appears anywhere with a hyphen (even though “country-music lyrics,” with a hyphen, wouldn’t be technically wrong; see CMOS 7.91 for a fuller explanation).
The phrase “time-clock punching,” however, seems to benefit from the hyphen, even though “time clock” is normally unhyphenated as a noun. That’s why “time-clock-punching employees”—where the whole phrase is used attributively—is our preference in CMOS (not only in chapter 5 but also in our hyphenation guide, section 1, under “noun + gerund”).
If you don’t like all those hyphens, try “employees who punch a time clock”—or, yes, use an en dash: “time clock–punching employees.” Some (many?) readers may not notice your en dash, but IYKYK.
Extra credit: What about “time-clock–punching employees,” with a hyphen and an en dash? That’s not a terrible idea (it does signal the hierarchy of relationships in the phrase), but it’s not Chicago style.