liquid_fuel_consumption: COICOP 04.5.3 does not include LPG #2642

policyengine_uk/variables/input/consumption/liquid_fuel_consumption.py documents the input as "liquid fuels such as heating oil and liquefied petroleum gas (COICOP 04.5.3)". COICOP puts liquefied hydrocarbons, butane and propane among them, under 04.5.2 (gas). So ONS Consumer Trends' 04.5.3 does not include LPG.

From PolicyEngine/microcosm#1383, Microcosm's UK frame writes bottled gas into this column (LCFS b018 and c45222), beside heating oil and paraffin, by an explicit ruling (PolicyEngine/microcosm#1278). It reports the bottled gas apart when it sets the column beside ONS's 04.5.3. Either way, the docstring should not say that 04.5.3 holds LPG. Proposed wording:

Annual household spending on heating oil, paraffin and bottled gas, mostly for heating homes off the gas grid. COICOP puts bottled gas (liquefied petroleum gas) under 04.5.2, gas, so a dataset that includes it is wider than ONS's 04.5.3.

Microcosm's frame does not level this column or solid_fuel_consumption to ONS's 04.5.3 or 04.5.4, and no formula reads either one yet. A note in both docstrings that a costing on them needs levelling to ONS first would help the next user.

Raised in Vahid's review of PolicyEngine/microcosm#1383 (item 8).