diff --git a/man/man3/cmark.3 b/man/man3/cmark.3
@@ -1,4 +1,4 @@
-.TH cmark 3 "May 05, 2017" "LOCAL" "Library Functions Manual"
+.TH cmark 3 "June 02, 2017" "LOCAL" "Library Functions Manual"
.SH
NAME
.PP
@@ -331,7 +331,8 @@ of the type, or \f[C]"<unknown>"\f[].
.PP
Returns the string contents of \f[I]node\f[], or an empty string if none
-is set.
+is set. Returns NULL if called on a node that does not have string
+content.
.PP
\fIint\f[] \fBcmark_node_set_literal\f[](\fIcmark_node *node\f[], \fIconst char *content\f[])
@@ -426,7 +427,8 @@ and 0 on failure.
.PP
Returns the URL of a link or image \f[I]node\f[], or an empty string if
-no URL is set.
+no URL is set. Returns NULL if called on a node that is not a link or
+image.
.PP
\fIint\f[] \fBcmark_node_set_url\f[](\fIcmark_node *node\f[], \fIconst char *url\f[])
@@ -440,7 +442,8 @@ on failure.
.PP
Returns the title of a link or image \f[I]node\f[], or an empty string
-if no title is set.
+if no title is set. Returns NULL if called on a node that is not a link
+or image.
.PP
\fIint\f[] \fBcmark_node_set_title\f[](\fIcmark_node *node\f[], \fIconst char *title\f[])
@@ -454,7 +457,8 @@ on failure.
.PP
Returns the literal "on enter" text for a custom \f[I]node\f[], or an
-empty string if no on_enter is set.
+empty string if no on_enter is set. Returns NULL if called on a
+non\-custom node.
.PP
\fIint\f[] \fBcmark_node_set_on_enter\f[](\fIcmark_node *node\f[], \fIconst char *on_enter\f[])
@@ -469,7 +473,8 @@ success 0 on failure.
.PP
Returns the literal "on exit" text for a custom \f[I]node\f[], or an
-empty string if no on_exit is set.
+empty string if no on_exit is set. Returns NULL if called on a
+non\-custom node.
.PP
\fIint\f[] \fBcmark_node_set_on_exit\f[](\fIcmark_node *node\f[], \fIconst char *on_exit\f[])
diff --git a/src/cmark.h b/src/cmark.h
@@ -265,7 +265,8 @@ CMARK_EXPORT
const char *cmark_node_get_type_string(cmark_node *node);
/** Returns the string contents of 'node', or an empty
- string if none is set.
+ string if none is set. Returns NULL if called on a
+ node that does not have string content.
*/
CMARK_EXPORT const char *cmark_node_get_literal(cmark_node *node);
@@ -334,7 +335,8 @@ CMARK_EXPORT const char *cmark_node_get_fence_info(cmark_node *node);
CMARK_EXPORT int cmark_node_set_fence_info(cmark_node *node, const char *info);
/** Returns the URL of a link or image 'node', or an empty string
- if no URL is set.
+ if no URL is set. Returns NULL if called on a node that is
+ not a link or image.
*/
CMARK_EXPORT const char *cmark_node_get_url(cmark_node *node);
@@ -344,7 +346,8 @@ CMARK_EXPORT const char *cmark_node_get_url(cmark_node *node);
CMARK_EXPORT int cmark_node_set_url(cmark_node *node, const char *url);
/** Returns the title of a link or image 'node', or an empty
- string if no title is set.
+ string if no title is set. Returns NULL if called on a node
+ that is not a link or image.
*/
CMARK_EXPORT const char *cmark_node_get_title(cmark_node *node);
@@ -354,7 +357,8 @@ CMARK_EXPORT const char *cmark_node_get_title(cmark_node *node);
CMARK_EXPORT int cmark_node_set_title(cmark_node *node, const char *title);
/** Returns the literal "on enter" text for a custom 'node', or
- an empty string if no on_enter is set.
+ an empty string if no on_enter is set. Returns NULL if called
+ on a non-custom node.
*/
CMARK_EXPORT const char *cmark_node_get_on_enter(cmark_node *node);
@@ -366,7 +370,8 @@ CMARK_EXPORT int cmark_node_set_on_enter(cmark_node *node,
const char *on_enter);
/** Returns the literal "on exit" text for a custom 'node', or
- an empty string if no on_exit is set.
+ an empty string if no on_exit is set. Returns NULL if
+ called on a non-custom node.
*/
CMARK_EXPORT const char *cmark_node_get_on_exit(cmark_node *node);