(though not one whose precise significance can be ascertained).
Heb. ben adam. The Son of Man in Mark sometimes clearly alludes to Dan 7.13–14 (8.38; 13.26; 14.62), but here it is ambiguous, as in v. 28. The scribes, as characters in the narrative, find the phrase confusing, but the audience would understand it as a title for Jesus based on a particular interpretation of Dan 7.13–14. Whatever its precise meaning, it focuses here on Jesus’ earthly authority (see also v. 28; Mt 8.20; 11.19; 12.32; Lk 6.22; 7.34; 9.58; 12.10). (HarperCollins)
