Dashes Replace Commas When the Element Has Internal Commas
The Dash
Rulebase Summary
When an element that needs commas around it (such as an appositive or nonessential clause) also has internal commas, use a pair of dashes to replace the commas around the element. This prevents confusion between the separating commas and the internal commas.
Examples
A. My three supervisors, Mr. Kim, Ms. Patel, and Dr. Reeves, all approved the report.
A. My three supervisors -- Mr. Kim, Ms. Patel, and Dr. Reeves -- all approved the report.
Dashes replace outer commas; internal commas stay.
A. His three partners, Clark, Nguyen, and Webb, were also present.
A. His three partners -- Clark, Nguyen, and Webb -- were also present.
Dashes replace commas when the element has internal commas.
Transcript Notes
This rule alleviates the confusion of having commas with different functions within and around the same element. Unless the element has internal punctuation, there is no reason to use dashes instead of commas. The dashes can be used whenever an element that needs commas around it also has commas within it, particularly when the dashes improve readability.
Style Guide References (2)
BGGP
BGGP