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node_modules/@zenuml/core/docs/inherited-vs-provided-from.md

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+What we should be looking at is `statement` which can be one of:
+
+1. Alt/Par/Opt/Loop
+1. Message
+1. Creation
+
+`stat`'s parent is always `block`. `block`'s parent is either `braceBlock`
+or `prog`. If it is `prog` we are looking the `starter`; if it is `braceBlock`,
+we need to find its parent message or creation and get their owners.
+
+There are two ways to decide where the message is from.
+One way is to deduce from its parent context - inherited from;
+the other way is to explicitly define it from its own context -
+provided from.
+
+## Inherited
+
+Sync message
+
+```
+A.m1 {
+  // m2 has an "inherited from" as `A`
+  m2
+}
+```
+
+Async message
+
+```
+A.m1 {
+  // m2 has an "inherited from" as `A`
+  B:m2
+}
+```
+
+## Provided
+
+Sync message
+
+```
+A.m1 {
+  // m2 has a "provided from" as `B`
+  B->C.m2
+
+}
+```
+
+Async message
+
+```
+A.m1 {
+  // m2 has a "provided from" as `B`
+  B->C:m2
+}
+```
+
+It is allowed to have a `provided from` that equals to its
+`inherited from`.
+
+# Discussion
+
+By definition, a root method has an `inherited from` as `Starter` or otherwise specified by `@StarterExp()`.
+
+`Starter`, unless it is explicitly defined, will not be displayed on the lifeline layer.