diff --git a/crates/tek_core/src/engine.rs b/crates/tek_core/src/engine.rs
index 29d146ff..6fdb692b 100644
--- a/crates/tek_core/src/engine.rs
+++ b/crates/tek_core/src/engine.rs
@@ -10,7 +10,7 @@ pub trait Engine: Send + Sync + Sized {
     /// Render target
     type Output: Output<Self>;
     /// Unit of length
-    type Unit: Number;
+    type Unit: Coordinate;
     /// Rectangle without offset
     type Size: Size<Self::Unit> + From<[Self::Unit;2]> + Debug + Copy;
     /// Rectangle with offset
diff --git a/crates/tek_core/src/lib.rs b/crates/tek_core/src/lib.rs
index 41744473..d02aca7e 100644
--- a/crates/tek_core/src/lib.rs
+++ b/crates/tek_core/src/lib.rs
@@ -54,35 +54,3 @@ pub type Usually<T> = Result<T, Box<dyn Error>>;
 
 /// Standard optional result type.
 pub type Perhaps<T> = Result<Option<T>, Box<dyn Error>>;
-
-/// Standard numeric type.
-pub trait Number: Send + Sync + Copy
-    + Add<Self, Output=Self>
-    + Sub<Self, Output=Self>
-    + Mul<Self, Output=Self>
-    + Div<Self, Output=Self>
-    + Ord + PartialEq + Eq
-    + Debug + Display + Default
-    + From<u16> + Into<u16>
-    + Into<f64>
-{
-    fn minus (self, other: Self) -> Self {
-        if self >= other {
-            self - other
-        } else {
-            0.into()
-        }
-    }
-}
-
-impl<T> Number for T where
-    T: Send + Sync + Copy
-        + Add<Self, Output=Self>
-        + Sub<Self, Output=Self>
-        + Mul<Self, Output=Self>
-        + Div<Self, Output=Self>
-        + Ord + PartialEq + Eq
-        + Debug + Display + Default
-        + From<u16> + Into<u16>
-        + Into<f64>
-{}
diff --git a/crates/tek_core/src/space.rs b/crates/tek_core/src/space.rs
index 6e94f5be..7bf26ce3 100644
--- a/crates/tek_core/src/space.rs
+++ b/crates/tek_core/src/space.rs
@@ -1,5 +1,37 @@
 use crate::*;
 
+/// Standard numeric type.
+pub trait Coordinate: Send + Sync + Copy
+    + Add<Self, Output=Self>
+    + Sub<Self, Output=Self>
+    + Mul<Self, Output=Self>
+    + Div<Self, Output=Self>
+    + Ord + PartialEq + Eq
+    + Debug + Display + Default
+    + From<u16> + Into<u16>
+    + Into<f64>
+{
+    fn minus (self, other: Self) -> Self {
+        if self >= other {
+            self - other
+        } else {
+            0.into()
+        }
+    }
+}
+
+impl<T> Coordinate for T where
+    T: Send + Sync + Copy
+        + Add<Self, Output=Self>
+        + Sub<Self, Output=Self>
+        + Mul<Self, Output=Self>
+        + Div<Self, Output=Self>
+        + Ord + PartialEq + Eq
+        + Debug + Display + Default
+        + From<u16> + Into<u16>
+        + Into<f64>
+{}
+
 pub struct FixedAxis<T> {
     pub start: T,
     pub point: Option<T>,
@@ -39,7 +71,7 @@ impl_axis_common!(ScaledAxis usize);
 // TODO: return impl Point and impl Size instead of [N;x]
 // to disambiguate between usage of 2-"tuple"s
 
-pub trait Size<N: Number> {
+pub trait Size<N: Coordinate> {
     fn x (&self) -> N;
     fn y (&self) -> N;
     #[inline] fn w (&self) -> N { self.x() }
@@ -56,17 +88,17 @@ pub trait Size<N: Number> {
     }
 }
 
-impl<N: Number> Size<N> for (N, N) {
+impl<N: Coordinate> Size<N> for (N, N) {
     fn x (&self) -> N { self.0 }
     fn y (&self) -> N { self.1 }
 }
 
-impl<N: Number> Size<N> for [N;2] {
+impl<N: Coordinate> Size<N> for [N;2] {
     fn x (&self) -> N { self[0] }
     fn y (&self) -> N { self[1] }
 }
 
-pub trait Area<N: Number>: Copy {
+pub trait Area<N: Coordinate>: Copy {
     fn x  (&self) -> N;
     fn y  (&self) -> N;
     fn w  (&self) -> N;
@@ -117,14 +149,14 @@ pub trait Area<N: Number>: Copy {
     }
 }
 
-impl<N: Number> Area<N> for (N, N, N, N) {
+impl<N: Coordinate> Area<N> for (N, N, N, N) {
     #[inline] fn x (&self) -> N { self.0 }
     #[inline] fn y (&self) -> N { self.1 }
     #[inline] fn w (&self) -> N { self.2 }
     #[inline] fn h (&self) -> N { self.3 }
 }
 
-impl<N: Number> Area<N> for [N;4] {
+impl<N: Coordinate> Area<N> for [N;4] {
     #[inline] fn x (&self) -> N { self[0] }
     #[inline] fn y (&self) -> N { self[1] }
     #[inline] fn w (&self) -> N { self[2] }
@@ -338,7 +370,7 @@ impl<T> Align<T> {
     }
 }
 
-fn align<T, N: Number, R: Area<N> + From<[N;4]>> (align: &Align<T>, outer: R, inner: R) -> Option<R> {
+fn align<T, N: Coordinate, R: Area<N> + From<[N;4]>> (align: &Align<T>, outer: R, inner: R) -> Option<R> {
     if outer.w() < inner.w() || outer.h() < inner.h() {
         None
     } else {
@@ -381,7 +413,7 @@ impl<E: Engine, T: Widget<Engine = E>> Widget for Align<T> {
 }
 
 /// Enforce fixed size of drawing area
-pub enum Fixed<U: Number, T> {
+pub enum Fixed<U: Coordinate, T> {
     /// Enforce fixed width
     X(U, T),
     /// Enforce fixed height
@@ -389,7 +421,7 @@ pub enum Fixed<U: Number, T> {
     /// Enforce fixed width and height
     XY(U, U, T),
 }
-impl<N: Number, T> Fixed<N, T> {
+impl<N: Coordinate, T> Fixed<N, T> {
     pub fn inner (&self) -> &T {
         match self { Self::X(_, i) => i, Self::Y(_, i) => i, Self::XY(_, _, i) => i, }
     }
@@ -417,7 +449,7 @@ impl<E: Engine, T: Widget<Engine = E>> Widget for Fixed<E::Unit, T> {
 }
 
 /// Enforce minimum size of drawing area
-pub enum Min<U: Number, T> {
+pub enum Min<U: Coordinate, T> {
     /// Enforce minimum width
     X(U, T),
     /// Enforce minimum height
@@ -425,7 +457,7 @@ pub enum Min<U: Number, T> {
     /// Enforce minimum width and height
     XY(U, U, T),
 }
-impl<N: Number, T> Min<N, T> {
+impl<N: Coordinate, T> Min<N, T> {
     pub fn inner (&self) -> &T {
         match self { Self::X(_, i) => i, Self::Y(_, i) => i, Self::XY(_, _, i) => i, }
     }
@@ -448,7 +480,7 @@ impl<E: Engine, T: Widget<Engine = E>> Widget for Min<E::Unit, T> {
 }
 
 /// Enforce maximum size of drawing area
-pub enum Max<U: Number, T> {
+pub enum Max<U: Coordinate, T> {
     /// Enforce maximum width
     X(U, T),
     /// Enforce maximum height
@@ -457,7 +489,7 @@ pub enum Max<U: Number, T> {
     XY(U, U, T),
 }
 
-impl<N: Number, T> Max<N, T> {
+impl<N: Coordinate, T> Max<N, T> {
     fn inner (&self) -> &T {
         match self { Self::X(_, i) => i, Self::Y(_, i) => i, Self::XY(_, _, i) => i, }
     }
@@ -480,7 +512,7 @@ impl<E: Engine, T: Widget<Engine = E>> Widget for Max<E:: Unit, T> {
 }
 
 /// Expand drawing area
-pub enum Grow<N: Number, T> {
+pub enum Grow<N: Coordinate, T> {
     /// Increase width
     X(N, T),
     /// Increase height
@@ -489,7 +521,7 @@ pub enum Grow<N: Number, T> {
     XY(N, N, T)
 }
 
-impl<N: Number, T> Grow<N, T> {
+impl<N: Coordinate, T> Grow<N, T> {
     fn inner (&self) -> &T {
         match self { Self::X(_, i) => i, Self::Y(_, i) => i, Self::XY(_, _, i) => i, }
     }
@@ -512,7 +544,7 @@ impl<E: Engine, T: Widget<Engine = E>> Widget for Grow<E::Unit, T> {
 }
 
 /// Shrink drawing area
-pub enum Shrink<N: Number, T> {
+pub enum Shrink<N: Coordinate, T> {
     /// Decrease width
     X(N, T),
     /// Decrease height
@@ -521,7 +553,7 @@ pub enum Shrink<N: Number, T> {
     XY(N, N, T),
 }
 
-impl<N: Number, T: Widget> Shrink<N, T> {
+impl<N: Coordinate, T: Widget> Shrink<N, T> {
     fn inner (&self) -> &T {
         match self { Self::X(_, i) => i, Self::Y(_, i) => i, Self::XY(_, _, i) => i, }
     }
@@ -553,7 +585,7 @@ impl<E: Engine, T: Widget<Engine = E>> Widget for Shrink<E::Unit, T> {
 }
 
 /// Shrink from each side
-pub enum Inset<N: Number, T> {
+pub enum Inset<N: Coordinate, T> {
     /// Decrease width
     X(N, T),
     /// Decrease height
@@ -562,14 +594,14 @@ pub enum Inset<N: Number, T> {
     XY(N, N, T),
 }
 
-impl<N: Number, T: Widget> Inset<N, T> {
+impl<N: Coordinate, T: Widget> Inset<N, T> {
     pub fn inner (&self) -> &T {
         match self { Self::X(_, i) => i, Self::Y(_, i) => i, Self::XY(_, _, i) => i, }
     }
 }
 
 /// Grow on each side
-pub enum Outset<N: Number, T> {
+pub enum Outset<N: Coordinate, T> {
     /// Increase width
     X(N, T),
     /// Increase height
@@ -578,7 +610,7 @@ pub enum Outset<N: Number, T> {
     XY(N, N, T),
 }
 
-impl<N: Number, T: Widget> Outset<N, T> {
+impl<N: Coordinate, T: Widget> Outset<N, T> {
     pub fn inner (&self) -> &T {
         match self { Self::X(_, i) => i, Self::Y(_, i) => i, Self::XY(_, _, i) => i, }
     }
@@ -623,7 +655,7 @@ impl<E: Engine, T: Widget<Engine = E>> Widget for Outset<E::Unit, T> {
 }
 
 /// Move origin point of drawing area
-pub enum Push<N: Number, T: Widget> {
+pub enum Push<N: Coordinate, T: Widget> {
     /// Move origin to the right
     X(N, T),
     /// Move origin downwards
@@ -632,7 +664,7 @@ pub enum Push<N: Number, T: Widget> {
     XY(N, N, T),
 }
 
-impl<N: Number, T: Widget> Push<N, T> {
+impl<N: Coordinate, T: Widget> Push<N, T> {
     pub fn inner (&self) -> &T {
         match self { Self::X(_, i) => i, Self::Y(_, i) => i, Self::XY(_, _, i) => i, }
     }
@@ -661,7 +693,7 @@ impl<E: Engine, T: Widget<Engine = E>> Widget for Push<E::Unit, T> {
 }
 
 /// Move origin point of drawing area
-pub enum Pull<N: Number, T: Widget> {
+pub enum Pull<N: Coordinate, T: Widget> {
     /// Move origin to the right
     X(N, T),
     /// Move origin downwards
@@ -670,7 +702,7 @@ pub enum Pull<N: Number, T: Widget> {
     XY(N, N, T),
 }
 
-impl<N: Number, T: Widget> Pull<N, T> {
+impl<N: Coordinate, T: Widget> Pull<N, T> {
     pub fn inner (&self) -> &T {
         match self { Self::X(_, i) => i, Self::Y(_, i) => i, Self::XY(_, _, i) => i, }
     }