diff --git a/example/glide_computer/CMakeLists.txt b/example/glide_computer/CMakeLists.txt
index 01e64578..d9f28018 100644
--- a/example/glide_computer/CMakeLists.txt
+++ b/example/glide_computer/CMakeLists.txt
@@ -22,6 +22,6 @@
 
 cmake_minimum_required(VERSION 3.2)
 
-add_library(glide_computer STATIC include/geographic.h glide_computer.cpp include/glide_computer.h)
+add_library(glide_computer STATIC glide_computer.cpp include/glide_computer.h)
 target_link_libraries(glide_computer PRIVATE mp-units::core-fmt PUBLIC mp-units::si mp-units::utility example_utils)
 target_include_directories(glide_computer PUBLIC include)
diff --git a/example/glide_computer/glide_computer.cpp b/example/glide_computer/glide_computer.cpp
index 3d1b1f6c..0eacceed 100644
--- a/example/glide_computer/glide_computer.cpp
+++ b/example/glide_computer/glide_computer.cpp
@@ -21,6 +21,7 @@
 // SOFTWARE.
 
 #include "glide_computer.h"
+#include <mp_units/format.h>
 #include <iostream>
 #include <numeric>
 #include <string_view>
@@ -48,7 +49,7 @@ std::vector<distance> task::make_leg_total_distances(const legs& legs)
   return res;
 }
 
-altitude terrain_level_alt(const task& t, const flight_point& pos)
+geographic::msl_altitude terrain_level_alt(const task& t, const flight_point& pos)
 {
   const task::leg& l = t.get_legs()[pos.leg_idx];
   const height alt_diff = l.end().alt - l.begin().alt;
@@ -58,7 +59,8 @@ altitude terrain_level_alt(const task& t, const flight_point& pos)
 // Returns `x` of the intersection of a glide line and a terrain line.
 // y = -x / glide_ratio + pos.alt;
 // y = (finish_alt - ground_alt) / dist_to_finish * x + ground_alt + min_agl_height;
-distance glide_distance(const flight_point& pos, const glider& g, const task& t, const safety& s, altitude ground_alt)
+distance glide_distance(const flight_point& pos, const glider& g, const task& t, const safety& s,
+                        geographic::msl_altitude ground_alt)
 {
   const auto dist_to_finish = t.get_distance() - pos.dist;
   return quantity_cast<isq::distance>(ground_alt + s.min_agl_height - pos.alt) /
@@ -150,8 +152,8 @@ void estimate(timestamp start_ts, const glider& g, const weather& w, const task&
   // estimate aircraft towing
   pos = tow(start_ts, pos, at);
 
-  // estimate the altitude needed to reach the finish line from this place
-  const altitude final_glide_alt =
+  // estimate the msl_altitude needed to reach the finish line from this place
+  const geographic::msl_altitude final_glide_alt =
     t.get_finish().alt + quantity_cast<isq::height>(t.get_distance() / glide_ratio(g.polar[0]));
 
   // how much height we still need to gain in the thermalls to reach the destination?
diff --git a/example/glide_computer/include/glide_computer.h b/example/glide_computer/include/glide_computer.h
index ad28d604..5b2f5edf 100644
--- a/example/glide_computer/include/glide_computer.h
+++ b/example/glide_computer/include/glide_computer.h
@@ -24,7 +24,6 @@
 
 #include "geographic.h"
 #include <mp_units/chrono.h>
-#include <mp_units/format.h>
 #include <mp_units/math.h>  // IWYU pragma: keep
 #include <mp_units/quantity_point.h>
 #include <mp_units/systems/isq/space_and_time.h>
@@ -54,14 +53,11 @@
 namespace glide_computer {
 
 // https://en.wikipedia.org/wiki/Flight_planning#Units_of_measurement
-inline constexpr struct mean_sea_level : mp_units::absolute_point_origin<mp_units::isq::height> {
-} mean_sea_level;
 QUANTITY_SPEC(rate_of_climb_speed, mp_units::isq::speed, mp_units::isq::height / mp_units::isq::time);
 
 // length
 using distance = mp_units::quantity<mp_units::isq::distance[mp_units::si::kilo<mp_units::si::metre>]>;
 using height = mp_units::quantity<mp_units::isq::height[mp_units::si::metre]>;
-using altitude = mp_units::quantity_point<mp_units::isq::altitude[mp_units::si::metre], mean_sea_level>;
 
 // time
 using duration = mp_units::quantity<mp_units::isq::duration[mp_units::si::second]>;
@@ -72,29 +68,7 @@ using timestamp = mp_units::quantity_point<mp_units::isq::time[mp_units::si::sec
 using velocity = mp_units::quantity<mp_units::isq::speed[mp_units::si::kilo<mp_units::si::metre> / mp_units::si::hour]>;
 using rate_of_climb = mp_units::quantity<rate_of_climb_speed[mp_units::si::metre / mp_units::si::second]>;
 
-// text output
-template<class CharT, class Traits>
-std::basic_ostream<CharT, Traits>& operator<<(std::basic_ostream<CharT, Traits>& os, const altitude& a)
-{
-  return os << a.absolute() << " AMSL";
-}
-
-}  // namespace glide_computer
-
-template<>
-struct STD_FMT::formatter<glide_computer::altitude> :
-    formatter<mp_units::quantity<mp_units::isq::altitude[mp_units::si::metre]>> {
-  template<typename FormatContext>
-  auto format(const glide_computer::altitude& a, FormatContext& ctx)
-  {
-    formatter<mp_units::quantity<mp_units::isq::altitude[mp_units::si::metre]>>::format(a.absolute(), ctx);
-    return STD_FMT::format_to(ctx.out(), " AMSL");
-  }
-};
-
 // definition of glide computer databases and utilities
-namespace glide_computer {
-
 struct glider {
   struct polar_point {
     velocity v;
@@ -118,7 +92,7 @@ struct weather {
 struct waypoint {
   std::string name;
   geographic::position<long double> pos;
-  altitude alt;
+  geographic::msl_altitude alt;
 };
 
 class task {
@@ -184,14 +158,17 @@ struct aircraft_tow {
 
 struct flight_point {
   timestamp ts;
-  altitude alt;
+  geographic::msl_altitude alt;
   std::size_t leg_idx = 0;
   distance dist{};
 };
 
-altitude terrain_level_alt(const task& t, const flight_point& pos);
+geographic::msl_altitude terrain_level_alt(const task& t, const flight_point& pos);
 
-constexpr height agl(altitude glider_alt, altitude terrain_level) { return glider_alt - terrain_level; }
+constexpr height agl(geographic::msl_altitude glider_alt, geographic::msl_altitude terrain_level)
+{
+  return glider_alt - terrain_level;
+}
 
 inline mp_units::quantity<mp_units::isq::length[mp_units::si::kilo<mp_units::si::metre>]> length_3d(distance dist,
                                                                                                     height h)
@@ -199,7 +176,8 @@ inline mp_units::quantity<mp_units::isq::length[mp_units::si::kilo<mp_units::si:
   return hypot(dist, h);
 }
 
-distance glide_distance(const flight_point& pos, const glider& g, const task& t, const safety& s, altitude ground_alt);
+distance glide_distance(const flight_point& pos, const glider& g, const task& t, const safety& s,
+                        geographic::msl_altitude ground_alt);
 
 void estimate(timestamp start_ts, const glider& g, const weather& w, const task& t, const safety& s,
               const aircraft_tow& at);
diff --git a/example/glide_computer_example.cpp b/example/glide_computer_example.cpp
index 88184977..bc8bf18b 100644
--- a/example/glide_computer_example.cpp
+++ b/example/glide_computer_example.cpp
@@ -36,8 +36,8 @@
 
 namespace {
 
+using namespace geographic;
 using namespace glide_computer;
-
 using namespace mp_units;
 
 auto get_gliders()
@@ -67,8 +67,8 @@ auto get_waypoints()
   using namespace geographic::literals;
   using namespace mp_units::international::unit_symbols;
   static const std::array waypoints = {
-    waypoint{"EPPR", {54.24772_N, 18.6745_E}, altitude{16. * ft}},   // N54°14'51.8" E18°40'28.2"
-    waypoint{"EPGI", {53.52442_N, 18.84947_E}, altitude{115. * ft}}  // N53°31'27.9" E18°50'58.1"
+    waypoint{"EPPR", {54.24772_N, 18.6745_E}, msl_altitude{16. * ft}},   // N54°14'51.8" E18°40'28.2"
+    waypoint{"EPGI", {53.52442_N, 18.84947_E}, msl_altitude{115. * ft}}  // N53°31'27.9" E18°50'58.1"
   };
   return waypoints;
 }
diff --git a/example/glide_computer/include/geographic.h b/example/include/geographic.h
similarity index 86%
rename from example/glide_computer/include/geographic.h
rename to example/include/geographic.h
index f1efa632..2eae3e50 100644
--- a/example/glide_computer/include/geographic.h
+++ b/example/include/geographic.h
@@ -24,8 +24,10 @@
 
 #include "ranged_representation.h"
 #include <mp_units/bits/fmt_hacks.h>
+#include <mp_units/format.h>
 #include <mp_units/math.h>
 #include <mp_units/quantity.h>
+#include <mp_units/quantity_point.h>
 #include <mp_units/systems/isq/space_and_time.h>
 #include <mp_units/systems/si/units.h>
 #include <compare>
@@ -35,6 +37,33 @@
 
 namespace geographic {
 
+// clang-format off
+inline constexpr struct mean_sea_level : mp_units::absolute_point_origin<mp_units::isq::altitude> {} mean_sea_level;
+// clang-format on
+
+using msl_altitude = mp_units::quantity_point<mp_units::isq::altitude[mp_units::si::metre], mean_sea_level>;
+
+// text output
+template<class CharT, class Traits>
+std::basic_ostream<CharT, Traits>& operator<<(std::basic_ostream<CharT, Traits>& os, const msl_altitude& a)
+{
+  return os << a.absolute() << " AMSL";
+}
+
+}  // namespace geographic
+
+template<>
+struct STD_FMT::formatter<geographic::msl_altitude> : formatter<geographic::msl_altitude::quantity_type> {
+  template<typename FormatContext>
+  auto format(const geographic::msl_altitude& a, FormatContext& ctx)
+  {
+    formatter<geographic::msl_altitude::quantity_type>::format(a.absolute(), ctx);
+    return STD_FMT::format_to(ctx.out(), " AMSL");
+  }
+};
+
+namespace geographic {
+
 template<typename T = double>
 using latitude =
   mp_units::quantity<mp_units::isq::angular_measure[mp_units::si::degree], ranged_representation<T, -90, 90>>;