The CATEEM software describes the analysis of a 17 channel EEG conducted from the position of the so-called 10-20 electrode system, based on a frequency analysis. With the help of the Fast Fourier Transformation it is calculated, out of which frequencies the successive four seconds-sections of an EEG signal could be put together. The data can be recorded and averaged for any time period. As the analysis produces infinite frequencies between 0,5 and 35 Hertz (waves per second), the frequencies for the quantitative description are divided into six sections which are named delta (0.86 – 4.5 Hz), theta (4.75 – 6.75 Hz), alpha, beta etc. for historical reasons.