cadrumo.core.percentage module¶
A rate expressed on the zero-to-one-hundred scale.
AEAT states rates as percentages: a prorrata of 87, a retencion of 19, an IVA rate of 21. The bound was written out at thirteen sites across the prorrata, bienes de inversion, withholding, orden-projection and asset models, all spelling the same two numbers.
This is a DIFFERENT quantity from UnitProportion,
not a loose spelling of it, and the two must never be collapsed: 21 means
twenty-one per cent here and would be a nonsense share there, while 0.21 is a
valid share and rounds to nothing as a percentage. A value crossing between the
two scales is converted deliberately at the boundary that converts it, and the
separate aliases are what make that boundary visible.
The interval is inclusive at both ends: a rate of nought and a rate of a hundred per cent are both real, and an exempt or fully-deductible case relies on it.