How should the flag be lowered half staff?

The US Flag Code, Title 4, Chapter 1, Section 7, Subsection m consistently uses the term "half-staff." The whitehouse.gov website also consistently uses the phrase "half-staff." The other term, "half-mast," is used in certain on-line dictionaries. This term has naval connotations because ships have masts. For the general public either term should be readily understood to mean the same thing.