This package contains a set of tools for constructing and coercing into and from the "mdate" class. This date class implements ISO 8601-2:2019(E) and allows regular dates and times to be annotated to express unspecified date or time components, approximate or uncertain components, ranges, and sets of dates. The package therefore retains, represents, and reasons about data and time imprecision, resolving to a single data/time only on demand. This is useful for describing and analysing temporal information, whether historical or recent, where date or time precision may vary.