CH column metadata: archives_i90.bs.sign

# `archives_i90.bs.sign` 'Subir'/'Bajar' for the band direction. Both are payments per §17 — don't net them. - **category**: dimension - **common_pitfalls**: - BS energy is UNSIGNED (always positive); both Subir and Bajar generate cobros per §17 BOE — never sum with sign as a multiplier