Inputs
Inputs are a type of data point that represents the values that are fed into your model.
The values are expected to vary frequently, both based on real-world data and because they'll be part of your 'what if?' questions you want to ask the model later.
Because of this, inputs can be may be linked directly to live property values from ARDI, or can be connected to data points - such as the outputs - of other models.
Constants are very similar to inputs, but they are usually much more static.
Inputs are available and writable (as long as they aren't linked to other models or live data) from OPC-UA.