diff --git a/src/extended.rs b/src/extended.rs
index 670bfee..63fcf6e 100644
--- a/src/extended.rs
+++ b/src/extended.rs
@@ -37,7 +37,7 @@ impl FromStr for Extended {
         };
         let split = s.split('.').collect::<Vec<_>>();
         match split.len() {
-            3 => {
+            4 => {
                 let major = split.first().unwrap().parse::<u16>()?;
                 let minor = split.get(1).unwrap().parse::<u16>()?;
                 let patch = split.get(2).unwrap().parse::<u16>()?;
diff --git a/src/lib.rs b/src/lib.rs
index 3558809..66249d0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,8 +1,13 @@
 mod error;
 mod extended;
 mod prerelease;
+mod rapid;
 mod semver;
+mod simple;
 
-pub use {error::Error, extended::Extended, prerelease::PreRelease, semver::SemVer};
+pub use {
+    error::Error, extended::Extended, prerelease::PreRelease, rapid::Rapid, semver::SemVer,
+    simple::Simple,
+};
 
 pub static MAX_U12: u16 = 4096;
diff --git a/src/rapid.rs b/src/rapid.rs
index e69de29..ef179a2 100644
--- a/src/rapid.rs
+++ b/src/rapid.rs
@@ -0,0 +1,95 @@
+use {
+    crate::{Error, PreRelease, MAX_U12},
+    serde::{Deserialize, Serialize},
+    std::{cmp::Ordering, fmt, str::FromStr},
+};
+
+#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
+pub struct Rapid {
+    pub major: u16,
+    pub minor: u16,
+    pub pre: PreRelease,
+}
+
+impl fmt::Display for Rapid {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}.{}", self.major, self.minor)?;
+        match self.pre {
+            PreRelease::None => Ok(()),
+            p => write!(f, "_{p}"),
+        }
+    }
+}
+
+impl FromStr for Rapid {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let (s, pre) = match s.split_once('_') {
+            Some((a, b)) => (a, b.parse::<PreRelease>()?),
+            None => (s, PreRelease::None),
+        };
+        let split = s.split('.').collect::<Vec<_>>();
+        match split.len() {
+            2 => {
+                let major = split.first().unwrap().parse::<u16>()?;
+                let minor = split.get(1).unwrap().parse::<u16>()?;
+                if major > MAX_U12 || minor > MAX_U12 {
+                    return Err(Error::Range);
+                }
+                Ok(Self { major, minor, pre })
+            }
+            _ => Err(Error::ParseSemver),
+        }
+    }
+}
+
+impl From<Rapid> for u64 {
+    fn from(value: Rapid) -> Self {
+        let major = u64::from(value.major) << 52;
+        let minor = u64::from(value.minor) << 40;
+        let pre = u64::from(u16::from(value.pre));
+        major | minor | pre
+    }
+}
+
+impl TryFrom<u64> for Rapid {
+    type Error = Error;
+
+    fn try_from(value: u64) -> Result<Self, Self::Error> {
+        let mut mask: u64 = 0o7777 << 52;
+        let major = (value & mask) >> 52;
+        mask = 0o7777 << 40;
+        let minor = (value & mask) >> 40;
+        mask = 0o37777;
+        let p = u16::try_from(value & mask)?;
+        let pre: PreRelease = p.try_into()?;
+        Ok(Self {
+            major: major.try_into()?,
+            minor: minor.try_into()?,
+            pre,
+        })
+    }
+}
+
+impl PartialEq for Rapid {
+    fn eq(&self, other: &Self) -> bool {
+        self.major == other.major && self.minor == other.minor && self.pre == other.pre
+    }
+}
+
+impl Eq for Rapid {}
+
+impl Ord for Rapid {
+    fn cmp(&self, other: &Self) -> Ordering {
+        let a = u64::from(*self);
+        let b = u64::from(*other);
+        a.cmp(&b)
+    }
+}
+
+impl PartialOrd for Rapid {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
diff --git a/src/simple.rs b/src/simple.rs
index e69de29..38fb3b9 100644
--- a/src/simple.rs
+++ b/src/simple.rs
@@ -0,0 +1,83 @@
+use {
+    crate::{Error, PreRelease, MAX_U12},
+    serde::{Deserialize, Serialize},
+    std::{cmp::Ordering, fmt, str::FromStr},
+};
+
+#[derive(Clone, Copy, Debug, Deserialize, Serialize)]
+pub struct Simple {
+    pub major: u16,
+    pub pre: PreRelease,
+}
+
+impl fmt::Display for Simple {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.major)?;
+        match self.pre {
+            PreRelease::None => Ok(()),
+            p => write!(f, "_{p}"),
+        }
+    }
+}
+
+impl FromStr for Simple {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let (s, pre) = match s.split_once('_') {
+            Some((a, b)) => (a, b.parse::<PreRelease>()?),
+            None => (s, PreRelease::None),
+        };
+        let major = s.parse::<u16>()?;
+        if major > MAX_U12 {
+            return Err(Error::Range);
+        }
+        Ok(Self { major, pre })
+    }
+}
+
+impl From<Simple> for u64 {
+    fn from(value: Simple) -> Self {
+        let major = u64::from(value.major) << 52;
+        let pre = u64::from(u16::from(value.pre));
+        major | pre
+    }
+}
+
+impl TryFrom<u64> for Simple {
+    type Error = Error;
+
+    fn try_from(value: u64) -> Result<Self, Self::Error> {
+        let mut mask: u64 = 0o7777 << 52;
+        let major = (value & mask) >> 52;
+        mask = 0o37777;
+        let p = u16::try_from(value & mask)?;
+        let pre: PreRelease = p.try_into()?;
+        Ok(Self {
+            major: major.try_into()?,
+            pre,
+        })
+    }
+}
+
+impl PartialEq for Simple {
+    fn eq(&self, other: &Self) -> bool {
+        self.major == other.major && self.pre == other.pre
+    }
+}
+
+impl Eq for Simple {}
+
+impl Ord for Simple {
+    fn cmp(&self, other: &Self) -> Ordering {
+        let a = u64::from(*self);
+        let b = u64::from(*other);
+        a.cmp(&b)
+    }
+}
+
+impl PartialOrd for Simple {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}