uml/state-machine-diagram.md

@@ -43,6 +43,8 @@ Alternatively, *time events* may also express precise instances of time, e.g., "
 
 - *Composite states* are also denoted as rectangles with rounded corners and a name.
 They contain at least one *region*, i.e., a fragment that may execute concurrently with other *regions*.
+If you use multiple *regions*, add a note to the *composite state* and declare if the *regions* are executed concurrently or sequentially (if latter, state the specific order of execution).
+*Regions* do not contain *transitions* to other *regions*.
 A single *region* in a composite state is not visible.
 Two or more *regions* are denoted by using dashed lines.
 These *regions* (or a single one) are then made up of nested *states* (called *substates*) and *transitions* (both denoted as previously introduced and see example below).