Vertical Group Attribute

VerticalGroup is used to gather properties together in a vertical group in the inspector. This doesn't do much in and of itself, but in combination with other groups, such as <see cref="HorizontalGroupAttribute"/> it can be very useful.
Vertical Group Multiple Stacked Boxes 

[HorizontalGroup("Split")]
[VerticalGroup("Split/Left")]
public InfoMessageType First;

[VerticalGroup("Split/Left")]
public InfoMessageType Second;

[HideLabel]
[VerticalGroup("Split/Right")]
public int A;

[HideLabel]
[VerticalGroup("Split/Right")]
public int B;

[TitleGroup("Multiple Stacked Boxes")]
[HorizontalGroup("Multiple Stacked Boxes/Split")]
[VerticalGroup("Multiple Stacked Boxes/Split/Left")]
[BoxGroup("Multiple Stacked Boxes/Split/Left/Box A")]
public int BoxA;

[BoxGroup("Multiple Stacked Boxes/Split/Left/Box B")]
public int BoxB;

[VerticalGroup("Multiple Stacked Boxes/Split/Right")]
[BoxGroup("Multiple Stacked Boxes/Split/Right/Box C")]
public int BoxC, BoxD, BoxE;