diff --git a/src/libopensc/apdu.c b/src/libopensc/apdu.c
index c0b3d3fb..bc296ffb 100644
--- a/src/libopensc/apdu.c
+++ b/src/libopensc/apdu.c
@@ -274,7 +274,7 @@ static int sc_check_apdu(sc_card_t *card, const sc_apdu_t *apdu)
 		    (apdu->flags & SC_APDU_FLAGS_CHAINING) == 0))
 			goto error;
 	} else if ((apdu->cse & SC_APDU_EXT) != 0) {
-		/* check if the card support extended APDUs */
+		/* check if the card supports extended APDUs */
 		if ((card->caps & SC_CARD_CAP_APDU_EXT) == 0) {
 			sc_debug(card->ctx, SC_LOG_DEBUG_NORMAL, "card doesn't support extended APDUs");
 			goto error;
diff --git a/src/libopensc/opensc.h b/src/libopensc/opensc.h
index 796cef0f..35667e71 100644
--- a/src/libopensc/opensc.h
+++ b/src/libopensc/opensc.h
@@ -193,7 +193,8 @@ struct sc_reader_driver {
 	const char *short_name;
 	struct sc_reader_operations *ops;
 
-	size_t max_send_size, max_recv_size;
+	size_t max_send_size; /* Max Lc supported by the reader layer */
+	size_t max_recv_size; /* Mac Le supported by the reader layer */
 	void *dll;
 };
 
@@ -367,12 +368,12 @@ typedef struct sc_card {
 
 	int type;			/* Card type, for card driver internal use */
 	unsigned long caps, flags;
-	unsigned int wait_resend_apdu;	/* Delay (msec) before responding to an SW12 = 6CXX */
+	unsigned int wait_resend_apdu;	/* Delay (msec) before responding to an SW = 6CXX */
 	int cla;
 	u8 atr[SC_MAX_ATR_SIZE];
 	size_t atr_len;
-	size_t max_send_size;
-	size_t max_recv_size;
+	size_t max_send_size; /* Max Lc supported by the card */
+	size_t max_recv_size; /* Max Le supported by the card */
 
 	struct sc_app_info *app[SC_MAX_CARD_APPS];
 	int app_count;