diff --git a/2021-07-19.md b/2021-07-19.md
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+- [[stpa]]
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diff --git a/system theoretic process analysis.md b/system theoretic process analysis.md
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@@ -29,5 +29,6 @@
 		- [[feedback]] can be derived from [[responsibilities]] (which information does the process model need to contain?)
 	- step three: [[identify unsafe control actions]]
 		- an [[unsafe control action]] is one that, in a particular context, will lead to a [[hazard]].
+		- it must include the actual (real) context in which the control action is unsafe; and it must be linked to a hazard. it shouldn't depend on
 		
 	
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