Various treatments were performed to lower Fb pulp DPv to approximately 1150. These treatments include endoglucanase (C endo ) and Celluclast (C cell ) cellulase hydrolyses, hypochlorous acid HOCl oxidation (H), ozone followed by alkaline extraction (ZEo) or hydrogen peroxide (ZP), and hydrogen peroxide stage at 100°C (P 100C ). Details of the experimental conditions are given in the Materials & Methods section. The resulting degraded Fb pulp samples showed identical MMD and minor differences in DP values (Table ). The only exception was pulp mix Fb 40% +Fb-Z(0.5)Eo 60% , represented in Figure along Fb-H(0.6) pulp. This sample was a blend made with 40% of starting pulp Fb and 60% of ozonated Fb-Z(0.5)Eo pulp. Compared to other samples, this pulp had a higher cellulose fraction dispersity Đ M (C) (Table ). This is a direct example of the superior level of details granted by SEC over pulp viscosity measurements. At a lower DPv of ~850, differences between MMD appeared (Figure ). Treatment H seemed to degrade the fibres more homogeneously than the ZP treatment leaving more long cellulose chains untouched and depolymerising hemicelluloses significantly (Figure ). These visual interpretations were confirmed by the Đ M (C) values reported in Table . The two cellulase treatments C endo and C cell changed the starting pulp MMD differently (Figure ). Endoglucanase (C endo treatment) was probably constrained to some parts of the fibres as some long cellulose chains remained intact, as observed on the high-M r end of the MMD. This observation is in accordance with past studies on endoglucanase stating that their action would be mostly limited to fibres surface ). On the other hand, the Celluclast® cocktail could penetrate the fibres down to their core ), ultimately breaking them as well as forming flocculated debris (see MorFi analyses in Table and SEM micrographs in Supplementary file) ). Part of the low-M r material generated during the hydrolyses such as short polysaccharides, oligosaccharides and monomeric sugars was probably lost during the pulp washing. The MMD thus represent the insoluble fibre fraction of these enzymatic hydrolyses. Discrepancies between DPv and DPw(C) values (Table ) are briefly discussed in the Supplementary file. It is interesting to note that a purely homogeneous degradation of paper cellulose, ie. randomly cleaving carbohydrates chains, would provoke a decrease of the dispersity down to Đ M = 2, whereas values below 2 would point out preferential scissions at the middle of the chain ). Here, the two cellulase hydrolysed samples, and Fb-H(1.5) have cellulose deconvoluted dispersity values Đ M (C) < 2 although it can be assumed that the enzymatic hydrolysis targeted specific spots of the fibres with a preference for short chains ). Here, it is probably the loss of very short cellulose chains with pulp washing that yield more monodisperse cellulose MMD instead of an expected increase of dispersity. Hence, at first glance, data derived from MMD do not seem enough per se for characterising the homogeneity degree of cellulose depolymerisation occurring within fibres. However, using MMD for monitoring the effect of each depolymerising chemical can help one to make assumptions on the topochemical aspects of the degradation.