Date & Time Types

Namespace: OpenEHR.RM.DataTypes.DateTime

All temporal types derive from DvTemporal<T> (which itself derives from DvQuantifiable<T>) and are based on ISO 8601. A key openEHR feature is support for partial values — for example a date of birth where only the year is known.

DvDate

An ISO 8601 calendar date, optionally partial.

// Complete date
var dob = new DvDate("1985-03-22");

// Year and month only (day unknown)
var approx = new DvDate("1985-03");

// Year only
var yearOnly = new DvDate("1985");

Partial precision is indicated by the length of the value string.

DvTime

An ISO 8601 time of day, optionally partial, optionally timezone-aware.

var appointmentTime = new DvTime("09:30:00+01:00");
var hourOnly        = new DvTime("09");

DvDateTime

The most commonly used temporal type. Combines date and time, always with at least year precision.

// Full ISO 8601 datetime with timezone
var recorded = new DvDateTime("2025-05-24T09:15:00+01:00");

// UTC
var utc = new DvDateTime("2025-05-24T08:15:00Z");

// Date only (time not recorded)
var dateOnly = new DvDateTime("2025-05-24");

Tip — Always store times with a timezone offset in clinical records. DateTimeOffset.Now.ToString("o") produces a suitable string.

DvDuration

An ISO 8601 duration (period), used for age, duration of symptoms, dosing intervals, etc.

// 1 year, 2 months, 3 days, 4 hours
var age = new DvDuration("P1Y2M3DT4H");

// 30 minutes
var halfHour = new DvDuration("PT30M");

// Negative duration (e.g. pre-conception)
var preConception = new DvDuration("-P280D");

Component	Symbol	Example
Years	Y	P2Y
Months	M	P3M
Weeks	W	P1W
Days	D	P10D
Hours	H	PT12H
Minutes	M	PT30M
Seconds	S	PT45S

Time Specification types

For recurring schedules (medication dosing, appointment series), see OpenEHR.RM.DataTypes.TimeSpecification:

• DvPeriodicTime — a repeating schedule described by an iCalendar expression
• DvGeneralTimeSpecification — a free-form schedule