diff --git a/Cargo.toml b/Cargo.toml
index ab907ca4..f776769f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -56,6 +56,7 @@ url = "2.1"
 walkdir = "2"
 xdg = "2.2"
 zstd = { version = "0.4", features = [ "bindgen" ] }
+nom = "5.1"
 
 [features]
 default = []
diff --git a/src/tools/systemd.rs b/src/tools/systemd.rs
index 557bac75..5f97848d 100644
--- a/src/tools/systemd.rs
+++ b/src/tools/systemd.rs
@@ -1,2 +1,3 @@
+pub mod time;
 pub mod types;
 pub mod parser;
diff --git a/src/tools/systemd/time.rs b/src/tools/systemd/time.rs
new file mode 100644
index 00000000..08725252
--- /dev/null
+++ b/src/tools/systemd/time.rs
@@ -0,0 +1,487 @@
+use std::collections::HashMap;
+
+use anyhow::{bail, Error};
+use lazy_static::lazy_static;
+use bitflags::bitflags;
+
+use nom::{
+    error::{context, ParseError, VerboseError},
+    bytes::complete::{tag, take_while1},
+    combinator::{map_res, all_consuming, opt, recognize},
+    sequence::{pair, preceded, tuple},
+    character::complete::{alpha1, space0, digit1},
+    multi::separated_nonempty_list,
+};
+
+type IResult<I, O, E = VerboseError<I>> = Result<(I, O), nom::Err<E>>;
+
+fn parse_error<'a>(i: &'a str, context: &'static str) -> nom::Err<VerboseError<&'a str>> {
+    let err = VerboseError { errors: Vec::new() };
+    let err =VerboseError::add_context(i, context, err);
+    nom::Err::Error(err)
+}
+
+bitflags!{
+    #[derive(Default)]
+    pub struct WeekDays: u8 {
+        const MONDAY = 1;
+        const TUESDAY = 2;
+        const WEDNESDAY = 4;
+        const THURSDAY = 8;
+        const FRIDAY = 16;
+        const SATURDAY = 32;
+        const SUNDAY = 64;
+    }
+}
+
+#[derive(Debug)]
+pub enum DateTimeValue {
+    Single(u32),
+    Range(u32, u32),
+    Repeated(u32, u32),
+}
+
+#[derive(Default, Debug)]
+pub struct CalendarEvent {
+    pub days: WeekDays,
+    pub second: Vec<DateTimeValue>, // todo: support float values
+    pub minute: Vec<DateTimeValue>,
+    pub hour: Vec<DateTimeValue>,
+}
+
+lazy_static! {
+    pub static ref TIME_SPAN_UNITS: HashMap<&'static str, f64> = {
+        let mut map = HashMap::new();
+
+        let second = 1.0;
+
+        map.insert("seconds", second);
+        map.insert("second", second);
+        map.insert("sec", second);
+        map.insert("s", second);
+
+        let msec = second / 1000.0;
+
+        map.insert("msec", msec);
+        map.insert("ms", msec);
+
+        let usec = msec / 1000.0;
+
+        map.insert("usec", usec);
+        map.insert("us", usec);
+        map.insert("µs", usec);
+
+        let nsec = usec / 1000.0;
+
+        map.insert("nsec", nsec);
+        map.insert("ns", nsec);
+
+        let minute = second * 60.0;
+
+        map.insert("minutes", minute);
+        map.insert("minute", minute);
+        map.insert("min", minute);
+        map.insert("m", minute);
+
+        let hour = minute * 60.0;
+
+        map.insert("hours", hour);
+        map.insert("hour", hour);
+        map.insert("hr", hour);
+        map.insert("h", hour);
+
+        let day = hour * 24.0 ;
+
+        map.insert("days", day);
+        map.insert("day", day);
+        map.insert("d", day);
+
+        let week = day * 7.0;
+
+        map.insert("weeks", week);
+        map.insert("week", week);
+        map.insert("w", week);
+
+        let month = 30.44 * day;
+
+        map.insert("months", month);
+        map.insert("month", month);
+        map.insert("M", month);
+
+        let year = 365.25 * day;
+
+        map.insert("years", year);
+        map.insert("year", year);
+        map.insert("y", year);
+
+        map
+    };
+}
+
+#[derive(Default)]
+pub struct TimeSpan {
+    pub nsec: u64,
+    pub usec: u64,
+    pub msec: u64,
+    pub seconds: u64,
+    pub minutes: u64,
+    pub hours: u64,
+    pub days: u64,
+    pub weeks: u64,
+    pub months: u64,
+    pub years: u64,
+}
+
+impl TimeSpan {
+
+    pub fn  new() -> Self {
+        Self::default()
+    }
+}
+
+impl From<TimeSpan> for f64 {
+    fn from(ts: TimeSpan) -> Self {
+        (ts.seconds as f64) +
+            ((ts.nsec as f64) / 1_000_000_000.0)  +
+            ((ts.usec as f64) / 1_000_000.0)  +
+            ((ts.msec as f64) / 1_000.0)  +
+            ((ts.minutes as f64) * 60.0)  +
+            ((ts.hours as f64) * 3600.0)  +
+            ((ts.days as f64) * 3600.0 * 24.0)  +
+            ((ts.weeks as f64) * 3600.0 * 24.0 * 7.0)  +
+            ((ts.months as f64) * 3600.0 * 24.0 * 30.44)  +
+            ((ts.years as f64) * 3600.0 * 24.0 * 365.25)
+    }
+}
+
+fn parse_u32(i: &str) -> IResult<&str, u32> {
+    map_res(recognize(digit1), str::parse)(i)
+}
+
+fn parse_u64(i: &str) -> IResult<&str, u64> {
+    map_res(recognize(digit1), str::parse)(i)
+}
+
+fn parse_weekday(i: &str) -> IResult<&str, WeekDays, VerboseError<&str>> {
+    let (i, text) = alpha1(i)?;
+
+    match text.to_ascii_lowercase().as_str() {
+        "monday" | "mon" => Ok((i, WeekDays::MONDAY)),
+        "tuesday" | "tue" => Ok((i, WeekDays::TUESDAY)),
+        "wednesday" | "wed" => Ok((i, WeekDays::WEDNESDAY)),
+        "thursday" | "thu" => Ok((i, WeekDays::THURSDAY)),
+        "friday" | "fri" => Ok((i, WeekDays::FRIDAY)),
+        "saturday" | "sat" => Ok((i, WeekDays::SATURDAY)),
+        "sunday" | "sun" => Ok((i, WeekDays::SUNDAY)),
+        _ => return Err(parse_error(text, "weekday")),
+    }
+}
+
+fn parse_weekdays_range(i: &str) -> IResult<&str, WeekDays> {
+    let (i, startday) = parse_weekday(i)?;
+
+    let generate_range = |start, end| {
+        let mut res = 0;
+        let mut pos = start;
+        loop {
+            res |= pos;
+            if pos >= end { break; }
+            pos = pos << 1;
+        }
+        WeekDays::from_bits(res).unwrap()
+    };
+
+    if let (i, Some((_, endday))) = opt(pair(tag(".."),parse_weekday))(i)? {
+        let start = startday.bits();
+        let end = endday.bits();
+        if start > end {
+            let set1 = generate_range(start, WeekDays::SUNDAY.bits());
+            let set2 = generate_range(WeekDays::MONDAY.bits(), end);
+            Ok((i, set1 | set2))
+        } else {
+            Ok((i, generate_range(start, end)))
+        }
+    } else {
+        Ok((i, startday))
+    }
+}
+
+fn parse_date_time_comp(i: &str) -> IResult<&str, DateTimeValue> {
+
+    let (i, value) = parse_u32(i)?;
+
+    if let (i, Some(end)) = opt(preceded(tag(".."), parse_u32))(i)? {
+        return Ok((i, DateTimeValue::Range(value, end)))
+    }
+
+    if i.starts_with("/") {
+        let i = &i[1..];
+        let (i, repeat) = parse_u32(i)?;
+        Ok((i, DateTimeValue::Repeated(value, repeat)))
+    } else {
+        Ok((i, DateTimeValue::Single(value)))
+    }
+}
+
+fn parse_date_time_comp_list(i: &str) -> IResult<&str, Vec<DateTimeValue>> {
+
+    if i.starts_with("*") {
+        return Ok((&i[1..], Vec::new()));
+    }
+
+    separated_nonempty_list(tag(","), parse_date_time_comp)(i)
+}
+
+fn parse_time_spec(i: &str) -> IResult<&str, (Vec<DateTimeValue>, Vec<DateTimeValue>, Vec<DateTimeValue>)> {
+
+    let (i, (hour, minute, opt_second)) = tuple((
+        parse_date_time_comp_list,
+        preceded(tag(":"), parse_date_time_comp_list),
+        opt(preceded(tag(":"), parse_date_time_comp_list)),
+    ))(i)?;
+
+    if let Some(second) = opt_second {
+        Ok((i, (hour, minute, second)))
+    } else {
+        Ok((i, (hour, minute, vec![DateTimeValue::Single(0)])))
+    }
+}
+
+pub fn parse_calendar_event(i: &str) -> Result<CalendarEvent, Error> {
+    match all_consuming(parse_calendar_event_incomplete)(i) {
+        Err(err) => bail!("unable to parse calendar event: {}", err),
+        Ok((_, ce)) => Ok(ce),
+    }
+}
+
+fn parse_calendar_event_incomplete(mut i: &str) -> IResult<&str, CalendarEvent> {
+
+    let mut has_dayspec = false;
+    let mut has_timespec = false;
+    let has_datespec = false;
+
+    let mut event = CalendarEvent::default();
+
+    if i.starts_with(|c: char| char::is_ascii_alphabetic(&c)) {
+
+        match i {
+            "minutely" => {
+                return Ok(("", CalendarEvent {
+                    second: vec![DateTimeValue::Single(0)],
+                    ..Default::default()
+                }));
+            }
+            "hourly" => {
+                return Ok(("", CalendarEvent {
+                    minute: vec![DateTimeValue::Single(0)],
+                    second: vec![DateTimeValue::Single(0)],
+                    ..Default::default()
+                }));
+            }
+            "daily" => {
+                return Ok(("", CalendarEvent {
+                    hour: vec![DateTimeValue::Single(0)],
+                    minute: vec![DateTimeValue::Single(0)],
+                    second: vec![DateTimeValue::Single(0)],
+                    ..Default::default()
+                }));
+            }
+            "monthly" | "weekly" | "yearly" | "quarterly" | "semiannually" => {
+                unimplemented!();
+            }
+            _ => { /* continue */ }
+        }
+
+        let (n, range_list) =  context(
+            "weekday range list",
+            separated_nonempty_list(tag(","), parse_weekdays_range)
+        )(i)?;
+
+        has_dayspec = true;
+
+        i = space0(n)?.0;
+
+        for range in range_list  { event.days.insert(range); }
+    }
+
+    // todo: support date specs
+
+    if let (n, Some((hour, minute, second))) = opt(parse_time_spec)(i)? {
+        event.hour = hour;
+        event.minute = minute;
+        event.second = second;
+        has_timespec = true;
+        i = n;
+    } else {
+        event.hour = vec![DateTimeValue::Single(0)];
+        event.minute = vec![DateTimeValue::Single(0)];
+        event.second = vec![DateTimeValue::Single(0)];
+    }
+
+    if !(has_dayspec || has_timespec || has_datespec) {
+        return Err(parse_error(i, "date or time specification"));
+    }
+
+    Ok((i, event))
+}
+
+fn parse_time_unit(i: &str) ->  IResult<&str, &str> {
+    let (n, text) = take_while1(|c: char| char::is_ascii_alphabetic(&c) || c == 'µ')(i)?;
+    if TIME_SPAN_UNITS.contains_key(&text) {
+        Ok((n, text))
+    } else {
+        Err(parse_error(text, "time unit"))
+    }
+}
+
+
+pub fn parse_time_span(i: &str) -> Result<TimeSpan, Error> {
+    match all_consuming(parse_time_span_incomplete)(i) {
+        Err(err) => bail!("unable to parse time span: {}", err),
+        Ok((_, ts)) => Ok(ts),
+    }
+}
+
+fn parse_time_span_incomplete(mut i: &str) -> IResult<&str, TimeSpan> {
+
+    let mut ts = TimeSpan::default();
+
+    loop {
+        i = space0(i)?.0;
+        if i.is_empty() { break; }
+        let (n, num) = parse_u64(i)?;
+        i = space0(n)?.0;
+
+        if let (n, Some(unit)) = opt(parse_time_unit)(i)? {
+            i = n;
+            match unit {
+                "seconds" | "second" | "sec" | "s" => {
+                    ts.seconds += num;
+                }
+                "msec" | "ms" => {
+                    ts.msec += num;
+                }
+                "usec" | "us" | "µs" => {
+                    ts.usec += num;
+                }
+                "nsec" | "ns" => {
+                    ts.nsec += num;
+                }
+                "minutes" | "minute" | "min" | "m" => {
+                    ts.minutes += num;
+                }
+                "hours" | "hour" | "hr" | "h" => {
+                    ts.hours += num;
+                }
+                "days" | "day" | "d" => {
+                    ts.days += num;
+                }
+                "weeks" | "week" | "w" => {
+                    ts.weeks += num;
+                }
+                "months" | "month" | "M" => {
+                    ts.months += num;
+                }
+                "years" | "year" | "y" => {
+                    ts.years += num;
+                }
+                _ => return Err(parse_error(unit, "internal error")),
+            }
+        } else {
+            ts.seconds += num;
+        }
+    }
+
+    Ok((i, ts))
+}
+
+pub fn verify_time_span<'a>(i: &'a str) -> Result<(), Error> {
+    parse_time_span(i)?;
+    Ok(())
+}
+
+pub fn verify_calendar_event(i: &str) -> Result<(), Error> {
+    parse_calendar_event(i)?;
+    Ok(())
+}
+
+#[cfg(test)]
+mod test {
+
+    use super::*;
+
+    fn test_event(v: &'static str) -> Result<(), Error> {
+        match parse_calendar_event(v) {
+            Ok(event) => println!("CalendarEvent '{}' => {:?}", v, event),
+            Err(err) => bail!("parsing '{}' failed - {}", v, err),
+        }
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_calendar_event_weekday() -> Result<(), Error> {
+        test_event("mon,wed..fri")?;
+        test_event("fri..mon")?;
+
+        test_event("mon")?;
+        test_event("MON")?;
+        test_event("monDay")?;
+        test_event("tue")?;
+        test_event("Tuesday")?;
+        test_event("wed")?;
+        test_event("wednesday")?;
+        test_event("thu")?;
+        test_event("thursday")?;
+        test_event("fri")?;
+        test_event("friday")?;
+        test_event("sat")?;
+        test_event("saturday")?;
+        test_event("sun")?;
+        test_event("sunday")?;
+
+        test_event("mon..fri")?;
+        test_event("mon,tue,fri")?;
+        test_event("mon,tue..wednesday,fri..sat")?;
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_time_span_parser() -> Result<(), Error> {
+
+        let test_value = |ts_str: &str, expect: f64| -> Result<(), Error> {
+            let ts = parse_time_span(ts_str)?;
+            assert_eq!(f64::from(ts), expect, "{}", ts_str);
+            Ok(())
+        };
+
+        test_value("2", 2.0)?;
+        test_value("2s", 2.0)?;
+        test_value("2sec", 2.0)?;
+        test_value("2second", 2.0)?;
+        test_value("2seconds", 2.0)?;
+
+        test_value(" 2s 2 s 2", 6.0)?;
+
+        test_value("1msec 1ms", 0.002)?;
+        test_value("1usec 1us 1µs", 0.000_003)?;
+        test_value("1nsec 1ns", 0.000_000_002)?;
+        test_value("1minutes 1minute 1min 1m", 4.0*60.0)?;
+        test_value("1hours 1hour 1hr 1h", 4.0*3600.0)?;
+        test_value("1days 1day 1d", 3.0*86400.0)?;
+        test_value("1weeks 1 week 1w", 3.0*86400.0*7.0)?;
+        test_value("1months 1month 1M", 3.0*86400.0*30.44)?;
+        test_value("1years 1year 1y", 3.0*86400.0*365.25)?;
+
+        test_value("2h", 7200.0)?;
+        test_value(" 2 h", 7200.0)?;
+        test_value("2hours", 7200.0)?;
+        test_value("48hr", 48.0*3600.0)?;
+        test_value("1y 12month", 365.25*24.0*3600.0 + 12.0*30.44*24.0*3600.0)?;
+        test_value("55s500ms", 55.5)?;
+        test_value("300ms20s 5day", 5.0*24.0*3600.0 + 20.0 + 0.3)?;
+
+        Ok(())
+    }
+}
diff --git a/src/tools/systemd/types.rs b/src/tools/systemd/types.rs
index c0d4b139..006e5cb2 100644
--- a/src/tools/systemd/types.rs
+++ b/src/tools/systemd/types.rs
@@ -21,15 +21,47 @@ pub const SYSTEMD_STRING_ARRAY_SCHEMA: Schema = ArraySchema::new(
     "Array of Strings", &SYSTEMD_STRING_SCHEMA)
     .schema();
 
+pub const SYSTEMD_TIMESPAN_ARRAY_SCHEMA: Schema = ArraySchema::new(
+    "Array of time spans", &SYSTEMD_TIMESPAN_SCHEMA)
+    .schema();
+
+pub const SYSTEMD_CALENDAR_EVENT_ARRAY_SCHEMA: Schema = ArraySchema::new(
+    "Array of calendar events", &SYSTEMD_CALENDAR_EVENT_SCHEMA)
+    .schema();
+
 #[api(
     properties: {
         "OnCalendar": {
-            type: Array,
+            schema: SYSTEMD_CALENDAR_EVENT_ARRAY_SCHEMA,
+            optional: true,
+        },
+        "OnActiveSec": {
+            schema: SYSTEMD_TIMESPAN_ARRAY_SCHEMA,
+            optional: true,
+        },
+        "OnBootSec": {
+            schema: SYSTEMD_TIMESPAN_ARRAY_SCHEMA,
+            optional: true,
+        },
+        "OnStartupSec": {
+            schema: SYSTEMD_TIMESPAN_ARRAY_SCHEMA,
+            optional: true,
+        },
+        "OnUnitActiveSec": {
+            schema: SYSTEMD_TIMESPAN_ARRAY_SCHEMA,
+            optional: true,
+        },
+        "OnUnitInactiveSec": {
+            schema: SYSTEMD_TIMESPAN_ARRAY_SCHEMA,
+            optional: true,
+        },
+        "RandomizedDelaySec": {
+            schema: SYSTEMD_TIMESPAN_SCHEMA,
+            optional: true,
+        },
+        "AccuracySec": {
+            schema: SYSTEMD_TIMESPAN_SCHEMA,
             optional: true,
-            items: {
-                description: "Calendar event expression.",
-                type: String,
-            },
         },
     },
 )]
@@ -37,12 +69,45 @@ pub const SYSTEMD_STRING_ARRAY_SCHEMA: Schema = ArraySchema::new(
 #[allow(non_snake_case)]
 /// Systemd Timer Section
 pub struct SystemdTimerSection {
-    /// Calender event list.
     #[serde(skip_serializing_if="Option::is_none")]
     pub OnCalendar: Option<Vec<String>>,
     ///  If true, the time when the service unit was last triggered is stored on disk.
     #[serde(skip_serializing_if="Option::is_none")]
     pub Persistent: Option<bool>,
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub OnActiveSec: Option<Vec<String>>,
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub OnBootSec: Option<Vec<String>>,
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub OnStartupSec: Option<Vec<String>>,
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub OnUnitActiveSec: Option<Vec<String>>,
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub OnUnitInactiveSec: Option<Vec<String>>,
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub RandomizedDelaySec: Option<String>,
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub AccuracySec: Option<String>,
+
+    /// Trigger when system clock jumps.
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub OnClockChange: Option<bool>,
+
+    /// Trigger when time zone changes.
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub OnTimezomeChange: Option<bool>,
+
+    /// The unit to activate when this timer elapses.
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub Unit: Option<String>,
+
+    /// If true, an elapsing timer will cause the system to resume from suspend.
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub WakeSystem: Option<bool>,
+
+    /// If true, an elapsed timer will stay loaded, and its state remains queryable.
+    #[serde(skip_serializing_if="Option::is_none")]
+    pub RemainAfterElapse: Option<bool>,
 }
 
 #[api(
@@ -138,3 +203,13 @@ pub enum ServiceStartup {
     /// Like 'simple', but use sd_notify to synchronize startup.
     Notify,
 }
+
+pub const SYSTEMD_TIMESPAN_SCHEMA: Schema = StringSchema::new(
+    "systemd time span")
+    .format(&ApiStringFormat::VerifyFn(super::time::verify_time_span))
+    .schema();
+
+pub const SYSTEMD_CALENDAR_EVENT_SCHEMA: Schema = StringSchema::new(
+    "systemd time span")
+    .format(&ApiStringFormat::VerifyFn(super::time::verify_calendar_event))
+    .schema();