Musicians and herring-bone trim.

[major bill]

US Army regulations authorized trim bars across the breast. This style of trim was referred to as "herring-bone" trim. I have seen that a modern term of this trim as "bird-cage" trim. Regardless the name the trim was intended to help identify field musicians. The color of the herring-bone trim matched the trim color of the unit the field musicians were assigned to. There was several other styles of musician's trim early in the War.

I will allow others to add details on Confederate musician's trim.

 

[major bill]

This is the standard style for infantry.

Note that US Marines had their own method of identify field musicians.