A trajectory can be thought of as a script that is being compiled and run behind the scenes. It uses a namespace to store variable names and values. There are two types of variables: custom variables and device node variables.
A custom variable is only used within the context of a trajectory (e.g., for a calculation), so its name and value are simply stored in the namespace. A device node variable not only has its name-value pair stored in the namespace, but the device node corresponding to the variable name also gets set to the variable’s value.
Note: If the device node belongs to an add-removable device and the device has not been added, then the trajectory’s variable defaults to being a custom variable.