diff --git a/barchart-udt-core/doc/epoll-review.md b/barchart-udt-core/doc/epoll-review.md
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+
+### Interest set 
+
+int CEPoll::add_usock(const int eid, const UDTSOCKET& u, const int* events)   
+int CEPoll::remove_usock(const int eid, const UDTSOCKET& u)   
+* only change presence of interest
+
+int CEPoll::update_events(const UDTSOCKET& uid, std::set<int>& eids, int events, bool enable)
+* only update result if interest present
+
+int CEPoll::wait(const int eid, set<UDTSOCKET>* readfds, set<UDTSOCKET>* writefds, int64_t msTimeOut, set<SYSSOCKET>* lrfds, set<SYSSOCKET>* lwfds)   
+* report result regardless if interest is present
+
+```
+m_mPolls(poll-id) -> m_sUDTSocksIn(socket-id)
+m_mPolls(poll-id) -> m_sUDTSocksOut(socket-id)
+m_mPolls(poll-id) -> m_sUDTSocksEx(socket-id)
+```
+
+### Result set
+
+void CUDT::addEPoll(const int eid)
+* add only UDT_EPOLL_IN UDT_EPOLL_OUT
+* insert into result if interest is present and has matching state
+   
+void CUDT::removeEPoll(const int eid)   
+* remove only UDT_EPOLL_IN UDT_EPOLL_OUT
+* erase from result
+
+int CEPoll::update_events(const UDTSOCKET& uid, std::set<int>& eids, int events, bool enable)
+* only update result if interest present
+   
+int CEPoll::wait(const int eid, set<UDTSOCKET>* readfds, set<UDTSOCKET>* writefds, int64_t msTimeOut, set<SYSSOCKET>* lrfds, set<SYSSOCKET>* lwfds)   
+* report result regardless if interest is present
+
+```
+m_mPolls(poll-id) -> m_sUDTReads(socket-id)
+m_mPolls(poll-id) -> m_sUDTWrites(socket-id)
+m_mPolls(poll-id) -> m_sUDTExcepts(socket-id)
+```
+
+### Epoll state in result
+
+UDT_EPOLL_ERR
+* is only set
+* never cleared
+* socket must be closed
+