diff --git a/include/slibtool/slibtool.h b/include/slibtool/slibtool.h
index 88e044c..233d80d 100644
--- a/include/slibtool/slibtool.h
+++ b/include/slibtool/slibtool.h
@@ -233,12 +233,14 @@ slbt_api void slbt_free_driver_ctx	(struct slbt_driver_ctx *);
 slbt_api int  slbt_get_unit_ctx		(const struct slbt_driver_ctx *, const char * path, struct slbt_unit_ctx **);
 slbt_api void slbt_free_unit_ctx	(struct slbt_unit_ctx *);
 
+/* execution context api */
 slbt_api int  slbt_get_exec_ctx		(const struct slbt_driver_ctx *, struct slbt_exec_ctx **);
 slbt_api void slbt_free_exec_ctx	(struct slbt_exec_ctx *);
 slbt_api void slbt_reset_arguments	(struct slbt_exec_ctx *);
 slbt_api void slbt_reset_placeholders	(struct slbt_exec_ctx *);
 slbt_api void slbt_disable_placeholders	(struct slbt_exec_ctx *);
 
+/* core api */
 slbt_api int  slbt_exec_compile		(const struct slbt_driver_ctx *, struct slbt_exec_ctx *);
 slbt_api int  slbt_exec_execute		(const struct slbt_driver_ctx *, struct slbt_exec_ctx *);
 slbt_api int  slbt_exec_install		(const struct slbt_driver_ctx *, struct slbt_exec_ctx *);