• mother
• father
• obstetrician
• anesthesiologist
• nurse
• researcher

Rarely do all these find themselves in the room at the same time, but their right of participation is never challenged. That such roles are potentially challengeable is illustrated at an earlier time when the researcher justifies her presence as she asks the anesthesiologist whether he minded her filming. He agreed and the issue of the filming did not reappear in the context of a challenge.

At other times, most of these people are absent, and yet, it is "clear" that this moment, like all the other are directly relevant to "hospital labor in late 20th United States." In similar fashion, all contraction times proceed differently, and yet it is also clear that all moments are directly related to "contraction" and distinguished from the non-contraction times by the behavior of all participants. On this basis it is possible to draw a canonical contraction (ideal type of a contraction, or structural model).

	Lonnie, Mimi and the anesthesiologist had been talking about the epidural and the catheter in her back. The obstetrician walks in, looks at the monitor and asks "what happened to the monitor".
	He rearranges the monitor belt
	Obstetrician get into position for the examination.

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