Ordinarily produces: mi2 sq mi (km2 km2).
If one of mi2 and km2 is omitted, it will be calculated by conversion of the other (which must be numerical or an error will be displayed).
Setting switch to any non-empty value causes the metric value to be displayed first.
Set round to define the degree of rounding (e.g. 1 for one decimal place).
Setting mag changes the wikilink behind km2 (for example, set it to 1 E06 to link to 1 E06 m²).