--- /dev/null
+notmuch/comapt
+
+This directory consists of two things:
+
+1. Small programs used by the notmuch configure script to test for the
+ availability of certain system features, (library functions, etc.).
+
+ For example: have_getline.c
+
+2. Compatibility implementations of those system features for systems
+ that don't provide their own versions.
+
+ For example: getline.c
+
+ The compilation of these files is made conditional on the output of
+ the test programs from [1].