- * - either in the current scope, but prior to the current field.
- * - or in a parent scope (or parent of parent ...) still in a field
- * prior to the current field position within the parents.
- * A reaching through a dynamic scoping (e.g. from payload structure to
- * event header structure), the parent fields are always entirely prior
- * to the child.
+ * - either in the same dynamic scope:
+ * - either in the current scope, but prior to the current field.
+ * - or in a parent scope (or parent of parent ...) still in a field
+ * prior to the current field position within the parents.
+ * - or in a different dynamic scope:
+ * - either in a upper dynamic scope (walk down a targeted scope from
+ * the dynamic scope root)
+ * - or in a lower dynamic scope (failure)
+ * The dynamic scope roots are linked together, so we can access the
+ * parent dynamic scope from the child dynamic scope by walking up to
+ * the parent.