The figure below shows a scheme of function calls in nsgportal. In the plug-in there are two main sets, or layers, of functions designated by the prefix pop__ and _nsg__. The _pop__ functions open a parameter entry window when called with fewer than the required arguments, else run directly without opening a window. The second class of nsgportal functions with prefix _nsg__ can be called directly from MATLAB command line or from other MATLAB scripts or functions. These functions perform lower-level processing than the pop functions. A plug-in function (eegplugin_nsgportal) manages the inclusion and appearance of an nsgportal item in the main EEGLAB window menu.

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