diff --git a/include/polarssl/x509.h b/include/polarssl/x509.h
index 008e795e..ad8049a 100644
--- a/include/polarssl/x509.h
+++ b/include/polarssl/x509.h
@@ -110,24 +110,27 @@
 
 /*
  * X.509 extension types
+ *
+ * Comments refer to the status for using certificates. Status can be
+ * different for writing certificates or reading CRLs or CSRs.
  */
 #define EXT_AUTHORITY_KEY_IDENTIFIER    (1 << 0)
 #define EXT_SUBJECT_KEY_IDENTIFIER      (1 << 1)
-#define EXT_KEY_USAGE                   (1 << 2)
+#define EXT_KEY_USAGE                   (1 << 2)    /* Parsed but not used */
 #define EXT_CERTIFICATE_POLICIES        (1 << 3)
 #define EXT_POLICY_MAPPINGS             (1 << 4)
-#define EXT_SUBJECT_ALT_NAME            (1 << 5)
+#define EXT_SUBJECT_ALT_NAME            (1 << 5)    /* Supported (DNS) */
 #define EXT_ISSUER_ALT_NAME             (1 << 6)
 #define EXT_SUBJECT_DIRECTORY_ATTRS     (1 << 7)
-#define EXT_BASIC_CONSTRAINTS           (1 << 8)
+#define EXT_BASIC_CONSTRAINTS           (1 << 8)    /* Supported */
 #define EXT_NAME_CONSTRAINTS            (1 << 9)
 #define EXT_POLICY_CONSTRAINTS          (1 << 10)
-#define EXT_EXTENDED_KEY_USAGE          (1 << 11)
+#define EXT_EXTENDED_KEY_USAGE          (1 << 11)   /* Parsed but not used */
 #define EXT_CRL_DISTRIBUTION_POINTS     (1 << 12)
 #define EXT_INIHIBIT_ANYPOLICY          (1 << 13)
 #define EXT_FRESHEST_CRL                (1 << 14)
 
-#define EXT_NS_CERT_TYPE                (1 << 16)
+#define EXT_NS_CERT_TYPE                (1 << 16)   /* Parsed (and then ?) */
 
 /*
  * Storage format identifiers
diff --git a/include/polarssl/x509_crt.h b/include/polarssl/x509_crt.h
index ee8f9e6..e3c8b18 100644
--- a/include/polarssl/x509_crt.h
+++ b/include/polarssl/x509_crt.h
@@ -72,18 +72,18 @@
 
     x509_buf issuer_id;         /**< Optional X.509 v2/v3 issuer unique identifier. */
     x509_buf subject_id;        /**< Optional X.509 v2/v3 subject unique identifier. */
-    x509_buf v3_ext;            /**< Optional X.509 v3 extensions. Only Basic Contraints are supported at this time. */
+    x509_buf v3_ext;            /**< Optional X.509 v3 extensions.  */
     x509_sequence subject_alt_names;    /**< Optional list of Subject Alternative Names (Only dNSName supported). */
 
     int ext_types;              /**< Bit string containing detected and parsed extensions */
     int ca_istrue;              /**< Optional Basic Constraint extension value: 1 if this certificate belongs to a CA, 0 otherwise. */
     int max_pathlen;            /**< Optional Basic Constraint extension value: The maximum path length to the root certificate. Path length is 1 higher than RFC 5280 'meaning', so 1+ */
 
-    unsigned char key_usage;    /**< Optional key usage extension value: See the values below */
+    unsigned char key_usage;    /**< Optional key usage extension value: See the values in x509.h */
 
     x509_sequence ext_key_usage; /**< Optional list of extended key usage OIDs. */
 
-    unsigned char ns_cert_type; /**< Optional Netscape certificate type extension value: See the values below */
+    unsigned char ns_cert_type; /**< Optional Netscape certificate type extension value: See the values in x509.h */
 
     x509_buf sig_oid2;          /**< Signature algorithm. Must match sig_oid1. */
     x509_buf sig;               /**< Signature: hash of the tbs part signed with the private key. */