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diff --git a/lib/memcasecmp.c b/lib/memcasecmp.c
index 2a255f1..a2e42e8 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)