Behavior trees are a formal, graphical modelling language used primarily in systems and software engineering. Behavior trees employ a well-defined notation to unambiguously represent the hundreds or even thousands of natural language requirements that are typically used to express the stakeholder needs [⇒ Focus On User Need] for a large-scale software-integrated system. wikipedia 
[⇒ Behavior ⇒ Traits]
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2021-04-09_**Notation**_34_35
The order of magnitude of a digit within a conventional number identifies how many times that digit is multiplied by ten. Instead of increasing the power of a digit by moving to the next position on the left (thousands, hundreds, tens, units), depth-value increases power by depth of nesting. Crossing a boundary outward changes the order of magnitude by one power-of-ten, more generally by one power of an arbitrary base.