Secondary brackets are a second level of staff grouping. They are positioned to the left of brackets and allow you to mark groups of staves within a bracketed group. In Dorico Pro, secondary brackets can appear as a brace or as a sub-bracket.
By default, secondary brackets appear as sub-brackets: thin lines with square corners that extend beyond the bracket. You can change the appearance of secondary brackets and hide/show them for adjacent identical instruments in bracketed groups in each layout independently.
You cannot show sub-sub-brackets in addition to braces, you can only show sub-sub-brackets in addition to sub-brackets.
You can input and delete sub-brackets from selected rhythmic positions using custom bracket/brace groups.
You can change various aspects of the appearance and position of secondary brackets, such as whether sub-brackets reach to the systemic barline or just to the bracket, in
.