add task-009, edit req-044

1 files changed, 11 insertions, 0 deletions

diff --git a/requirements/tasks/task-009.md b/requirements/tasks/task-009.md
new file mode 100644
index 0000000..55d5637
--- /dev/null
+++ b/requirements/tasks/task-009.md
@@ -0,0 +1,11 @@
+# task-009
+
+Any commands sent to Schist's SMS interface must be unambiguous. That is, it
+must be difficult to send a valid command which does not mean what the user
+intended to mean.
+
+This can be guaranteed by writing automated tests to verify that semantically
+distinct commands are sufficiently distinct by a suitable measure, such as
+Levenshtein distance.
+
+Source: req-044