diff --git a/db/coords.go b/coords/convert.go
similarity index 50%
rename from db/coords.go
rename to coords/convert.go
index 7ee926e..04380cc 100644
--- a/db/coords.go
+++ b/coords/convert.go
@@ -1,4 +1,4 @@
-package db
+package coords
 
 //https://bitbucket.org/s_l_teichmann/mtsatellite/src/e1bf980a2b278c570b3f44f9452c9c087558acb3/common/coords.go?at=default&fileviewer=file-view-default
 const (
@@ -10,17 +10,17 @@ const (
 )
 
 
-func CoordToPlain(x, y, z int) int64 {
-	return int64(z)<<(2*numBitsPerComponent) +
-		int64(y)<<numBitsPerComponent +
-		int64(x)
+func CoordToPlain(c MapBlockCoords) int64 {
+	return int64(c.Z)<<(2*numBitsPerComponent) +
+		int64(c.Y)<<numBitsPerComponent +
+		int64(c.X)
 }
 
-func unsignedToSigned(i int16) int16 {
+func unsignedToSigned(i int16) int {
 	if i < maxPositive {
-		return i
+		return int(i)
 	}
-	return i - maxPositive*2
+	return int(i - maxPositive*2)
 }
 
 // To match C++ code.
@@ -32,11 +32,12 @@ func pythonModulo(i int16) int16 {
 	return modulo - -i&mask
 }
 
-func PlainToCoord(i int64) (int, int, int) {
-	x := unsignedToSigned(pythonModulo(int16(i)))
-	i = (i - int64(x)) >> numBitsPerComponent
-	y := unsignedToSigned(pythonModulo(int16(i)))
-	i = (i - int64(x)) >> numBitsPerComponent
-	z := unsignedToSigned(pythonModulo(int16(i)))
-	return int(x), int(y), int(z)
+func PlainToCoord(i int64) MapBlockCoords {
+	c := MapBlockCoords{}
+	c.X = unsignedToSigned(pythonModulo(int16(i)))
+	i = (i - int64(c.X)) >> numBitsPerComponent
+	c.Y = unsignedToSigned(pythonModulo(int16(i)))
+	i = (i - int64(c.Y)) >> numBitsPerComponent
+	c.Z = unsignedToSigned(pythonModulo(int16(i)))
+	return c
 }
diff --git a/coords/convert_test.go b/coords/convert_test.go
new file mode 100644
index 0000000..fe766a4
--- /dev/null
+++ b/coords/convert_test.go
@@ -0,0 +1,42 @@
+package coords
+
+import (
+  "testing"
+  "github.com/sirupsen/logrus"
+)
+
+var log *logrus.Entry
+func init(){
+	log = logrus.WithFields(logrus.Fields{"prefix": "coords/convert_test"})
+}
+
+func testCoordConvert(t *testing.T, mb MapBlockCoords){
+  log.WithFields(logrus.Fields{"coords":mb}).Info("MapblockCoords")
+
+  p := CoordToPlain(mb)
+  log.WithFields(logrus.Fields{"plain":p}).Info("MapblockCoords")
+
+  mb2 := PlainToCoord(p)
+  log.WithFields(logrus.Fields{"coords2":mb2}).Info("MapblockCoords")
+
+
+  if mb.X != mb2.X {
+    t.Fatal("X mismatch")
+  }
+
+  if mb.Y != mb2.Y {
+    t.Fatal("Y mismatch")
+  }
+
+  if mb.Z != mb2.Z {
+    t.Fatal("Z mismatch")
+  }
+
+}
+
+func TestConvertPlainMapBlock(t *testing.T){
+  testCoordConvert(t, NewMapBlockCoords(10, 0, -10))
+  testCoordConvert(t, NewMapBlockCoords(-2048, 2047, -10))
+  testCoordConvert(t, NewMapBlockCoords(-3, 0, 2047)) //0...2047
+
+}
diff --git a/coords/mapblockcoords.go b/coords/mapblockcoords.go
new file mode 100644
index 0000000..3db8d38
--- /dev/null
+++ b/coords/mapblockcoords.go
@@ -0,0 +1,9 @@
+package coords
+
+type MapBlockCoords struct {
+  X,Y,Z int
+}
+
+func NewMapBlockCoords(x,y,z int) MapBlockCoords {
+  return MapBlockCoords{X:x, Y:y, Z:z}
+}