dev/multiarch: Add use cases

1 files changed, 34 insertions, 0 deletions

diff --git a/dev/multiarch.mdwn b/dev/multiarch.mdwn
index 0669fba..fce463c 100644
--- a/dev/multiarch.mdwn
+++ b/dev/multiarch.mdwn
@@ -99,3 +99,37 @@ the architecture-qualified names.
 [wuc-mas-arch-indep-files]: https://wiki.ubuntu.com/MultiarchSpec#Architecture-independent_files_in_multiarch_packages
 [wuc-mas-control-fields]: https://wiki.ubuntu.com/MultiarchSpec#Binary_package_control_fields
 [spf-fields-bin]: http://specs.proteanos.com/spf-2.0/fields.html#fields-bin
+
+
+Use Cases
+=========
+
+**Run-time dependency on a utility:**  Only the native architecture of the
+utility dependency is available in the downloaded feed lists, and the dependency
+is not architecture-qualified.  The native architecture will be installed.
+
+**Run-time dependency on a library:**  Multiple architectures of the library
+dependency may be available, and the dependency must be qualified with the
+native architecture.
+
+**Run-time dependency on a language extension:**  Despite technically being a
+shared object file, only the native architecture of the language extension
+dependency is available in the downloaded feed lists, and the dependency is not
+architecture-qualified.  The language extension dependency in turn depends on a
+language interpreter, which is also not architecture-qualified.  The native
+architecture of both will be installed.
+
+**Build-time dependency on a utility:**  Only the build architecture of the
+utility dependency is available in the downloaded feed lists, and the dependency
+is not architecture-qualified.  The build architecture will be installed.
+
+**Build-time dependency on a library:**  Multiple architectures of the library
+dependency are available, and the dependency must be qualified with the host
+architecture.
+
+**Build-time dependency on a language extension:**  Despite technically being a
+shared object file, only the native architecture of the language extension
+dependency is available in the downloaded feed lists, and the dependency is not
+architecture-qualified.  The language extension dependency in turn depends on a
+language interpreter, which is also not architecture-qualified.  The native
+architecture of both will be installed.