How to understand EEG topographic map

The topographic map can only simply and intuitively represent the potential distribution recorded by the electrode (so it depends on whether the electrode is placed on the scalp or skull). Because of the well-known EEG inverse problem, the recording of scalp electrode can not be accurately located. ?

But generally speaking, a specific task or a specific ERP component has a relatively stable and consistent topographic map. For example, the famous semantic N400, grammar P600 and so on. However, this is not absolute, because new experimental designs have found that specific ERP components also present different topographic maps in different task States.