What is the significance of the parameter "quality_threshold = 0.23" in nominal.ini?

[SchwarzEM]

And is there any useful way in which this parameter can be tuned? For instance, if I used HINGE to assemble reads that have already been error-corrected and trimmed by another program (e.g., Canu), do I still want "quality_threshold = 0.23", or would a different value make more sense?