diff --git a/src/protocol/clock.rs b/src/protocol/clock/mod.rs
similarity index 98%
rename from src/protocol/clock.rs
rename to src/protocol/clock/mod.rs
index a72f3699e..6e925df3c 100644
--- a/src/protocol/clock.rs
+++ b/src/protocol/clock/mod.rs
@@ -1,5 +1,5 @@
 use std::num::IntErrorKind;
-pub use std::time::Duration;
+use std::time::Duration;
 
 pub type DurationSinceUnixEpoch = Duration;
 
@@ -240,9 +240,12 @@ mod stopped_clock {
 
             #[test]
             fn it_should_get_app_start_time() {
-                const TIME_AT_WRITING_THIS_TEST: Duration = Duration::new(1662983731, 000022312);
+                const TIME_AT_WRITING_THIS_TEST: Duration = Duration::new(1662983731, 22312);
                 assert!(get_app_start_time() > TIME_AT_WRITING_THIS_TEST);
             }
         }
     }
 }
+
+pub mod timeextent;
+pub mod timeextentmaker;
diff --git a/src/protocol/clock/timeextent.rs b/src/protocol/clock/timeextent.rs
new file mode 100644
index 000000000..370b32ff4
--- /dev/null
+++ b/src/protocol/clock/timeextent.rs
@@ -0,0 +1,112 @@
+use std::num::{IntErrorKind, TryFromIntError};
+use std::time::Duration;
+
+/// Count fixed sized increments. Provides the product of the increment and its count.
+pub trait Extent: Sized + Default {
+    type Increment;
+    type Count;
+    type Product;
+
+    fn new(size: &Self::Increment, quantity: &Self::Count) -> Self;
+
+    fn add(&self, add: Self::Count) -> Result<Self, IntErrorKind>;
+    fn sub(&self, sub: Self::Count) -> Result<Self, IntErrorKind>;
+
+    fn get(&self) -> Result<Option<Self::Product>, TryFromIntError>;
+    fn get_next(&self) -> Result<Option<Self::Product>, TryFromIntError>;
+}
+
+pub type TimeExtentIncrement = Duration;
+pub type TimeExtentIncrementSeconds = u64;
+pub type TimeExtentCount = u64;
+pub type TimeExtentExtent = TimeExtentIncrement;
+
+#[derive(Debug, Default, Hash, PartialEq, Eq)]
+pub struct TimeExtent {
+    pub size: TimeExtentIncrement,
+    pub quantity: TimeExtentCount,
+}
+
+impl TimeExtent {
+    pub const fn from_sec(size: TimeExtentIncrementSeconds, quantity: &TimeExtentCount) -> Self {
+        Self {
+            size: TimeExtentIncrement::from_secs(size),
+            quantity: *quantity,
+        }
+    }
+}
+
+impl Extent for TimeExtent {
+    type Increment = TimeExtentIncrement;
+    type Count = TimeExtentCount;
+    type Product = TimeExtentExtent;
+
+    fn new(size: &Self::Increment, quantity: &Self::Count) -> Self {
+        Self {
+            size: *size,
+            quantity: *quantity,
+        }
+    }
+
+    fn add(&self, add: Self::Count) -> Result<Self, IntErrorKind> {
+        match self.quantity.checked_add(add) {
+            None => Err(IntErrorKind::PosOverflow),
+            Some(quantity) => Ok(Self {
+                size: self.size,
+                quantity,
+            }),
+        }
+    }
+
+    fn sub(&self, sub: Self::Count) -> Result<Self, IntErrorKind> {
+        match self.quantity.checked_sub(sub) {
+            None => Err(IntErrorKind::NegOverflow),
+            Some(quantity) => Ok(Self {
+                size: self.size,
+                quantity,
+            }),
+        }
+    }
+
+    fn get(&self) -> Result<Option<Self::Product>, TryFromIntError> {
+        match u32::try_from(self.quantity) {
+            Err(error) => Err(error),
+            Ok(quantity) => Ok(self.size.checked_mul(quantity)),
+        }
+    }
+
+    fn get_next(&self) -> Result<Option<Self::Product>, TryFromIntError> {
+        match u32::try_from(self.quantity) {
+            Err(e) => Err(e),
+            Ok(quantity) => match quantity.checked_add(1) {
+                None => Ok(None),
+                Some(quantity) => match self.size.checked_mul(quantity) {
+                    None => Ok(None),
+                    Some(extent) => Ok(Some(extent)),
+                },
+            },
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+
+    use std::time::Duration;
+
+    use crate::protocol::clock::timeextent::{Extent, TimeExtent};
+
+    #[test]
+    fn it_should_get_the_total_time_of_a_period() {
+        assert_eq!(TimeExtent::default().get().unwrap().unwrap(), Duration::ZERO);
+
+        assert_eq!(
+            TimeExtent::from_sec(12, &12).get().unwrap().unwrap(),
+            Duration::from_secs(144)
+        );
+        assert_eq!(
+            TimeExtent::from_sec(12, &12).get_next().unwrap().unwrap(),
+            Duration::from_secs(156)
+        );
+    }
+}
diff --git a/src/protocol/clock/timeextentmaker.rs b/src/protocol/clock/timeextentmaker.rs
new file mode 100644
index 000000000..6979d2825
--- /dev/null
+++ b/src/protocol/clock/timeextentmaker.rs
@@ -0,0 +1,88 @@
+use std::num::TryFromIntError;
+use std::time::Duration;
+
+use super::timeextent::{Extent, TimeExtent, TimeExtentCount, TimeExtentIncrement};
+use super::{ClockType, StoppedClock, TimeNow, WorkingClock};
+
+pub trait MakeTimeExtent<Clock>: Sized
+where
+    Clock: TimeNow,
+{
+    fn now(size: &TimeExtentIncrement) -> Option<Result<TimeExtent, TryFromIntError>> {
+        Clock::now()
+            .as_nanos()
+            .checked_div((*size).as_nanos())
+            .map(|quantity| match TimeExtentCount::try_from(quantity) {
+                Err(error) => Err(error),
+                Ok(quantity) => Ok(TimeExtent::new(size, &quantity)),
+            })
+    }
+
+    fn now_add(size: &TimeExtentIncrement, add_time: &Duration) -> Option<Result<TimeExtent, TryFromIntError>> {
+        match Clock::add(add_time) {
+            None => None,
+            Some(time) => {
+                time.as_nanos()
+                    .checked_div(size.as_nanos())
+                    .map(|quantity| match TimeExtentCount::try_from(quantity) {
+                        Err(error) => Err(error),
+                        Ok(quantity) => Ok(TimeExtent::new(size, &quantity)),
+                    })
+            }
+        }
+    }
+    fn now_sub(size: &TimeExtentIncrement, sub_time: &Duration) -> Option<Result<TimeExtent, TryFromIntError>> {
+        match Clock::sub(sub_time) {
+            None => None,
+            Some(time) => {
+                time.as_nanos()
+                    .checked_div(size.as_nanos())
+                    .map(|quantity| match TimeExtentCount::try_from(quantity) {
+                        Err(error) => Err(error),
+                        Ok(quantity) => Ok(TimeExtent::new(size, &quantity)),
+                    })
+            }
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct ExtentClock<const T: usize> {}
+
+pub type WorkingClockExtentMaker = ExtentClock<{ ClockType::WorkingClock as usize }>;
+
+pub type StoppedClockExtentMaker = ExtentClock<{ ClockType::StoppedClock as usize }>;
+
+impl MakeTimeExtent<WorkingClock> for WorkingClockExtentMaker {}
+
+impl MakeTimeExtent<StoppedClock> for StoppedClockExtentMaker {}
+
+#[cfg(not(test))]
+pub type DefaultClockExtentMaker = WorkingClockExtentMaker;
+
+#[cfg(test)]
+pub type DefaultClockExtentMaker = StoppedClockExtentMaker;
+
+#[cfg(test)]
+mod tests {
+    use std::time::Duration;
+
+    use crate::protocol::clock::timeextent::TimeExtent;
+    use crate::protocol::clock::timeextentmaker::{DefaultClockExtentMaker, MakeTimeExtent};
+    use crate::protocol::clock::{DefaultClock, DurationSinceUnixEpoch, StoppedTime};
+
+    #[test]
+    fn it_should_get_the_current_period() {
+        assert_eq!(
+            DefaultClockExtentMaker::now(&Duration::from_secs(2)).unwrap().unwrap(),
+            TimeExtent::from_sec(2, &0)
+        );
+
+        DefaultClock::local_set(&DurationSinceUnixEpoch::from_secs(12387687123));
+
+        assert_eq!(
+            DefaultClockExtentMaker::now(&Duration::from_secs(2)).unwrap().unwrap(),
+            TimeExtent::from_sec(2, &6193843561)
+        );
+    }
+}