(a) Overview illustrations of the two sets of DIY spikes designed (set 1 and 2, respectively) and each set contains a full-length isoform and four shorter isoforms that harbor connected genetic variation in positions 5 to 35 (marked in red) and 100 bp downstream exclusions. (b) Cumulative percentage of spiked-in molecules that had its most 5’ base within the five first bases on the designed spike-in sequence. (c) Table summarizing correct and incorrect assignment of read pairs towards each diySpike isoform. (d) Histogram showing the read depth over the diySpikes, that is the number of read pairs per observed molecule. (e) Fraction of molecules assigned to a unique isoform or compatible with two or more isoforms as a function of the unique number of read pairs from each molecule.