谁来给我详细解释下“注册孔定位的用户函数”每一句代码啊，非常感谢啊！

sys601

/*注册孔定位的用户函数*/
2 C" K( z6 P! g3 xint rpo_routine_hole(tag_t obj_id)
{
% Y; U4 Q( z2 q* r: i4 Jint irc;
uf_list_p_t edge_list;
1 L& d9 K* L6 \9 I% qtag_t obj_id_target[1],obj_id_tool[1];
/ \- ~" u" k. q0 xchar *constraint_value[]={"0.0"};
char *constraint_array[]={"PARA_DIST_PARMS"};
int target_qualifier[]={UF_MODL_ARC_CENTER};
9 U9 Z5 y& k5 C: v1 ?' yint tool_qualifier[]={UF_MODL_ARC_CENTER};
UF_MODL_ask_feat_edges(obj_id, &edge_list );
UF_MODL_ask_list_item(edge_list, 0, &obj_id_tool[0]);
9 Y) ?- d% K5 h9 h* X/ }UF_MODL_delete_list(&edge_list);
3 l; k2 W. ]5 i% ^# F/ {obj_id_target[0] = target_edge;
irc=UF_MODL_create_rpo_constraints(obj_id,NULL_TAG,NULL_TAG,obj_id_target,
target_qualifier,obj_id_tool,tool_qualifier,constraint_value,constraint_array,1);
return irc;
}