-the number of clients in an application, and so on.
-
-\li <b>\c TRACE_host_variable_[set|add|sub] (const char *variable, double
-value)</b>:
-Set the value of a given user variable. It is important to remind that
-the value of this variable is always associated to the host. The host
-that will be used when these functions are called is the one returned by
-the function \c MSG_host_self().
+the number of clients in an application (for hosts), and so on.
+
+\li <b>\c TRACE_[host|link]_variable_[set|add|sub] (const char *[host|link], const char *variable, double value)</b>:
+Set the value of a given user variable for a given host/link. The value
+of this variable is always associated to the host/link. The host/link
+parameters should be its name as the one listed in the platform file.
+
+\li <b>\c TRACE_[host|link]_variable_[set|add|sub]_with_time (double time, const char *[host|link], const char *variable, double value)</b>:
+Same as TRACE_[host|link]_variable_[set|add|sub], but let user specify
+the time used to trace it. Users can specify a time that is not the
+simulated clock time as defined by the core simulator. This allows
+a fine-grain control of time definition, but should be used with
+caution since the trace can be inconsistent if resource utilization
+traces are also traced.
+
+\li <b>\c TRACE_link_srcdst_variable_[set|add|sub] (const char *src, const char *dst, const char *variable, double value)</b>:
+Same as TRACE_link_variable_[set|add|sub], but now users specify a source and
+destination hosts (as the names from the platform file). The tracing library
+will get the corresponding route that connects those two hosts (src and dst) and
+[set|add|sub] the value's variable for all the links of the route.
+
+\li <b>\c TRACE_link_srcdst_variable_[set|add|sub]_with_time (double time, const char *src, const char *dst, const char *variable, double value)</b>:
+Same as TRACE_link_srcdst_variable_[set|add|sub], but user specify a time different from the simulated time.