Sometimes your inputs or outputs may need to use a function or you may just want to add code to your neural networks. In this window you can specify where to put you code snippet and whether to insert it into the training and/or indicator formulas.
For example, if one of your inputs is Williams %R and you have an Amibroker function that calculates it, you can add a function to your code by setting placement to 'Function' and inserting into to 'Both' since the function will be need for both training and running the neural network. Once you add this function to your project by clicking ok, you can use it for your inputs and outputs.