Aside from renaming `Length` as fraction, this points immediately to a check: if they are fractions and they need to cover the whole year, they should add up to 1. Maybe worth adding this as an issue within a collection of issues related to input validation.
_Originally posted by @dalonsoa in https://github.com/EnergySystemsModellingLab/MUSE_2.0/pull/67#pullrequestreview-2112011345_