The most relevant parameter, being the fraction of single links fSL, is fixed, and the fit is carriedout with one fixed parameter, automatically stabilising the whole procedure. Afterwards, the fSLparameter is incremented by a small step ΔfSL (here ΔfSL = 0.01 = 1%), and the fit evaluated again. This is done over the whole range of expected a1-values (here: between 0.1 and 0.9). The total RMSE is plotted (see Figure and), and the minimum is detected and is taken as the best-fit result. The stability of the fit was tested by using randomly determined starting parameters within a physically meaningful range. The presented error bars (confidence boundaries) were chosen such that the corresponding curves present suitable envelopes for the data up to a 30 % increase of the nRMSE minimum value. Since the minimum is taken as reference value, error bars for the presented data are not symmetric and represent the range of possible values. We stress that the error bars describe a possible systematic error (possible fitting bias, e. g. arising from the fact that a single A.-l. function may not be a perfect approximation to a signal fraction), which means that trends in the best-fit results for different samples are meaningful even if they are smaller than this systematic variation range. Other sources of errors, e.g., rf-pulse miscalibration or ambiguities in the distinction of different connectivities are not (or in the latter case only partially) included into the error bars. The fitting ambiguity between DL and HOC is circumvented by evaluating mostly the better defined single-link fraction and comparing it to the sum of other connectivities.