add comment

diff --git a/lib/memcasecmp.c b/lib/memcasecmp.c
index 2a255f19d802ae8eb25069c6348e1766449d566f..a2e42e8ecfa60134713464cf0fa6f1781cf0b901 100644 (file)
--- a/lib/memcasecmp.c
+++ b/lib/memcasecmp.c
@@ -39,7 +39,9 @@
 
 #include "memcasecmp.h"
 
-/* Like memcmp, but ignore differences in case.  */
+/* Like memcmp, but ignore differences in case.
+   Convert to upper case (not lower) before comparing so that
+   join -i works with sort -f.  */
 
 int
 memcasecmp (vs1, vs2, n)