Recode urban to area for micro data
add_area.pipmd.RdDeprecated. Superseded by apply_recode_spec(), which recodes
urban -> area (and normalises subnatid via shift_subnatid()) from
the YAML recode specification (inst/extdata/recode_spec.yml). Kept only
for backward compatibility; calling this method now emits a deprecation
warning via base::.Deprecated().
Usage
# S3 method for class 'pipmd'
add_area(dt)