This has bothered me all morning, because-- you know-- I am all about authority! Just ask the experts!
Fortunately, the two
|page 352 of Harbrace Handbook of English by John C. Hodges. 1941. Harcourt, Brace and Company: New York, Chicago|
A. subheadings of the first degree
1. subheadings of the second degree
a. subheadings of the third degree
(1). subheadings of the fourth degree
I could be wrong, but I remember MSWord offering a choice of the parenthetical subheading. Of course, that's when I used MSWord back in the