Inconsistent behaviour

[pjljvandelaar]

This sysml

action singleton_merge_ref {
	action A;
	action B;
	merge C;
	action D;
	
	first A;
		then B;
		then C;
		then D; 
}

is interpreted as

While this sysml code

action singleton_merge {
	action A;
	action B;
	action D;
	
	first A;
		then B;
		then merge C;
		then D; 
}

is interpreted as

For me, this different interpretation came as a total surprise.
Is this different behaviour really in the standard?
If so, could you add an explanation to the documentation?
If not, is the implementation wrong?

Thanks in advance for your answer,
Pierre