diff --git a/library/lms.c b/library/lms.c
index 72f9319..e0f5946 100644
--- a/library/lms.c
+++ b/library/lms.c
@@ -80,8 +80,27 @@
 
 #define D_CONST_LEN           (2)
 static const unsigned char D_LEAF_CONSTANT_BYTES[D_CONST_LEN] = {0x82, 0x82};
-static const unsigned char D_INTERNAL_CONSTANT_BYTES[D_CONST_LEN] = {0x83, 0x83};
+static const unsigned char D_INTR_CONSTANT_BYTES[D_CONST_LEN] = {0x83, 0x83};
 
+
+/* Calculate the value of a leaf node of the merkle tree (which is a hash of a
+ * public key and some other parameters like the leaf index). This function
+ * implements RFC8554 section 5.3, in the case where r >= 2^h.
+ *
+ *  \param params              The LMS parameter set, the underlying LMOTS
+ *                             parameter set, and I value which describe the key
+ *                             being used.
+ *
+ *  \param pub_key             The public key of the private whose index
+ *                             corresponds to the index of this leaf node. This
+ *                             is a hash output.
+ *
+ *  \param r_node_idx          The index of this node in the merkle tree. Note
+ *                             that the root node of the merkle tree is
+ *                             1-indexed.
+ *
+ *  \param out                 The output node value, which is a hash output.
+ */
 static int create_merkle_leaf_value( const mbedtls_lms_parameters_t *params,
                                      unsigned char *pub_key,
                                      unsigned int r_node_idx,
@@ -134,6 +153,28 @@
     return( ret );
 }
 
+/* Calculate the value of an internal node of the merkle tree (which is a hash
+ * of a public key and some other parameters like the node index). This function
+ * implements RFC8554 section 5.3, in the case where r < 2^h.
+ *
+ *  \param params              The LMS parameter set, the underlying LMOTS
+ *                             parameter set, and I value which describe the key
+ *                             being used.
+ *
+ *  \param left_node           The value of the child of this node which is on
+ *                             the left-hand side. As with all nodes on the
+ *                             merkle tree, this is a hash output.
+ *
+ *  \param right_node          The value of the child of this node which is on
+ *                             the right-hand side. As with all nodes on the
+ *                             merkle tree, this is a hash output.
+ *
+ *  \param r_node_idx          The index of this node in the merkle tree. Note
+ *                             that the root node of the merkle tree is
+ *                             1-indexed.
+ *
+ *  \param out                 The output node value, which is a hash output.
+ */
 static int create_merkle_internal_value( const mbedtls_lms_parameters_t *params,
                                          const unsigned char *left_node,
                                          const unsigned char *right_node,
@@ -363,6 +404,20 @@
 
 #ifdef MBEDTLS_LMS_PRIVATE
 
+/* Calculate a full merkle tree based on a private key. This function
+ * implements RFC8554 section 5.3, and is used to generate a public key (as the
+ * public key is the root node of the merkle tree).
+ *
+ *  \param ctx                 The LMS private context, containing a parameter
+ *                             set and private key material consisting of both
+ *                             public and private OTS.
+ *
+ *  \param tree                The output tree, which is 2^(H + 1) hash outputs.
+ *                             In the case of H=10 we have 2048 tree nodes (of
+ *                             which 1024 of them are leaf nodes). Note that
+ *                             because the merkle tree root is 1-indexed, the 0
+ *                             index tree node is never used.
+ */
 static int calculate_merkle_tree( mbedtls_lms_private_t *ctx,
                                   unsigned char *tree )
 {
@@ -406,6 +461,18 @@
     return( 0 );
 }
 
+/* Calculate a path from a leaf node of the merkle tree to the root of the tree,
+ * and return the full path. This function implements RFC8554 section 5.4.1, as
+ * the merkle path is the main component of an LMS signature.
+ *
+ *  \param ctx                 The LMS private context, containing a parameter
+ *                             set and private key material consisting of both
+ *                             public and private OTS.
+ *
+ *  \param leaf_node_id        Which leaf node to calculate the path from.
+ *
+ *  \param tree                The output path, which is H hash outputs.
+ */
 static int get_merkle_path( mbedtls_lms_private_t *ctx,
                             unsigned int leaf_node_id,
                             unsigned char *path )