# description
Defines the types of relationships between actions.

# concept[].definition
The action must be performed before the start of the related action.

# concept[].definition
The action must be performed before the related action.

# concept[].definition
The action must be performed before the end of the related action.

# concept[].definition
The action must be performed concurrent with the start of the related action.

# concept[].definition
The action must be performed concurrent with the related action.

# concept[].definition
The action must be performed concurrent with the end of the related action.

# concept[].definition
The action must be performed after the start of the related action.

# concept[].definition
The action must be performed after the related action.

# concept[].definition
The action must be performed after the end of the related action.