+/*
+ * User-variables related functions
+ */
+/* for host variables */
+XBT_PUBLIC(void) TRACE_host_variable_declare (const char *var);
+XBT_PUBLIC(void) TRACE_host_variable_declare_with_color (const char *var, const char *color);
+XBT_PUBLIC(void) TRACE_host_variable_set (const char *host, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_host_variable_add (const char *host, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_host_variable_sub (const char *host, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_host_variable_set_with_time (double time, const char *host, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_host_variable_add_with_time (double time, const char *host, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_host_variable_sub_with_time (double time, const char *host, const char *variable, double value);
+
+/* for link variables */
+XBT_PUBLIC(void) TRACE_link_variable_declare (const char *var);
+XBT_PUBLIC(void) TRACE_link_variable_declare_with_color (const char *var, const char *color);
+XBT_PUBLIC(void) TRACE_link_variable_set (const char *link, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_link_variable_add (const char *link, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_link_variable_sub (const char *link, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_link_variable_set_with_time (double time, const char *link, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_link_variable_add_with_time (double time, const char *link, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_link_variable_sub_with_time (double time, const char *link, const char *variable, double value);
+
+/* for link variables, but with src and dst used for get_route */
+XBT_PUBLIC(void) TRACE_link_srcdst_variable_set (const char *src, const char *dst, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_link_srcdst_variable_add (const char *src, const char *dst, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_link_srcdst_variable_sub (const char *src, const char *dst, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_link_srcdst_variable_set_with_time (double time, const char *src, const char *dst, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_link_srcdst_variable_add_with_time (double time, const char *src, const char *dst, const char *variable, double value);
+XBT_PUBLIC(void) TRACE_link_srcdst_variable_sub_with_time (double time, const char *src, const char *dst, const char *variable, double value);