From Omniversalis

Documentation for this module may be created at Module:Convert/extra/doc

-- Extra conversion data used by Module:Convert.
-- [[Module:Convert/data]] defines all units and is transcluded in all pages
-- where [[Module:Convert]] is used. Testing new units by editing that module
-- would invalidate the cache for all affected pages.
-- For quick changes and experiments with new units, this module can be edited.
-- Since this module is transcluded in only a small number of pages, changes
-- should cause little server overhead and should propagate quickly.
-- If a unit is defined in the data module, any definition here is ignored,
-- so defining the same unit in both modules is not an error.
-- A unit defined here can refer to units that are also defined here, and
-- can refer to units defined in the data module.
-- Periodically, those extra units that are wanted permanently can be removed
-- from here after being added to [[Module:Convert/data]].

local extra_units = {
    ["cda"] = {
	name1    = "cuerda",
	symbol   = "cda",
	utype    = "area",
	scale    = 3930.395625,
	default  = "ha acre",
    ["PSh"] = {
	name1    = "Pferdestärkenstunde",
	symbol   = "PSh",
	utype    = "energy",
	scale    = 2647795.5,
	default  = "kWh",
	link     = "Horsepower-hour",
    ["/mi2"] = {  -- need to define to avoid automatic-per-unit bug when converting with /km2
	target   = "/sqmi",

return { extra_units = extra_units }