1 files changed, 3 insertions, 0 deletions
diff --git a/lib/pam.h b/lib/pam.h
index 24a27e81..2726092b 100644
--- a/lib/pam.h
+++ b/lib/pam.h
@@ -71,6 +71,9 @@ struct pam {
            Before Netpbm 10.32, this was rather different.  It simply
            described for convenience the plainness of the format indicated
            by 'format'.
+
+           This is meaningless when 'format' is PAM_FORMAT, as PAM does not
+           have plain and raw variations.
         */
     int height;  /* Height of image in rows */
     int width;