Is it a Roman numeral?
See also
Other code detectors:
is_ca_postal_code(),
is_country_code(),
is_http_status(),
is_uk_postcode(),
is_unix_time(),
is_us_state(),
is_version(),
is_zip_code()
Examples
is_roman(c("XIV", "MMXXIV", "IIII", "", NA))
#> [1] TRUE TRUE FALSE FALSE NA