+ /**
+ * This function decides, if a node should appear in a schedule.
+ * May be NULL.
+ *
+ * @param block_env The block environment.
+ * @param irn The node.
+ * @return 1, if the node should be scheduled, 0 if not.
+ */
+ int (*to_appear_in_schedule)(void *block_env, const ir_node *irn);
+
+ /**
+ * This function gets executed after a node finally has been made ready.
+ * May be NULL.
+ *
+ * @param block_env The block environment.
+ * @param irn The node made ready.
+ * @param pred The previously scheduled node.
+ */
+ void (*node_ready)(void *block_env, ir_node *irn, ir_node *pred);
+
+ /**
+ * This function gets executed after a node finally has been selected.
+ * May be NULL.
+ *
+ * @param block_env The block environment.
+ * @param irn The selected node.
+ */
+ void (*node_selected)(void *block_env, ir_node *irn);
+
+ /**
+ * Returns the execution time of node irn.
+ * May be NULL.
+ *
+ * @param block_env The block environment.
+ * @param irn The selected node.
+ */
+ unsigned (*exectime)(void *block_env, const ir_node *irn);
+
+ /**
+ * Calculates the latency of executing cycle curr_cycle of node curr in cycle pred_cycle
+ * of node pred.
+ * May be NULL.
+ *
+ * @param block_env The block environment.
+ * @param pred The previous node.
+ * @param pred_cycle The previous node execution cycle.
+ * @param curr The current node.
+ * @param curr_cycle The current node execution cycle.
+ */
+ unsigned (*latency)(void *block_env, const ir_node *pred, int pred_cycle, const ir_node *curr, int curr_cycle);
+
+ /**
+ * Called after a block has been scheduled.
+ * May be NULL.
+ *
+ * @param env The environment.
+ * @param block_env The per block environment as returned by init_block().
+ */
+ void (*finish_block)(void *block_env);
+
+ /**
+ * Called after a whole graph has been scheduled.
+ * May be NULL.
+ *
+ * @param env The environment.
+ */
+ void (*finish_graph)(void *env);
+};
+
+
+/**
+ * A trivial selector, that just selects the first ready node.
+ */
+extern const list_sched_selector_t trivial_selector;
+
+/**
+ * A trivial selector that selects a pseudo-random-node (deterministic).
+ */
+extern const list_sched_selector_t random_selector;
+
+/**
+ * A selector that tries to minimize the register pressure.
+ * @note Not really operational yet.
+ */
+extern const list_sched_selector_t reg_pressure_selector;
+
+/**
+ * A selector based on trace scheduling as introduced by Muchnik[TM]
+ */
+extern const list_sched_selector_t muchnik_selector;
+
+/**
+ * A selector based on trace scheduling as introduced by Muchnik[TM]
+ * but using the Mueller heuristic selector.
+ */
+extern const list_sched_selector_t heuristic_selector;
+
+/**
+ * A selector based on the strong normal form theorem (ie minimizing
+ * the register pressure).
+ */
+extern const list_sched_selector_t normal_selector;