HCONV and HCONVLIST are 32bit handles.

dlls/user/ddeml.spec

 2 pascal -ret16 DdeInitialize(ptr segptr long long) DdeInitialize16
 3 pascal -ret16 DdeUninitialize(long) DdeUninitialize16
 4 pascal DdeConnectList(long word word word ptr) DdeConnectList16
-5 pascal DdeQueryNextServer(word word) DdeQueryNextServer16
-6 pascal -ret16 DdeDisconnectList(word) DdeDisconnectList16
+5 pascal DdeQueryNextServer(long long) DdeQueryNextServer16
+6 pascal -ret16 DdeDisconnectList(long) DdeDisconnectList16
 7 pascal DdeConnect(long long long ptr) DdeConnect16
 8 pascal -ret16 DdeDisconnect(long) DdeDisconnect16
-9 pascal -ret16 DdeQueryConvInfo (word long ptr) DdeQueryConvInfo16
-10 pascal -ret16 DdeSetUserHandle(word long long) DdeSetUserHandle16
+9 pascal -ret16 DdeQueryConvInfo (long long ptr) DdeQueryConvInfo16
+10 pascal -ret16 DdeSetUserHandle(long long long) DdeSetUserHandle16
 11 pascal DdeClientTransaction(ptr long long long s_word s_word long ptr) DdeClientTransaction16
-12 pascal -ret16 DdeAbandonTransaction(long word long) DdeAbandonTransaction16
+12 pascal -ret16 DdeAbandonTransaction(long long long) DdeAbandonTransaction16
 13 pascal -ret16 DdePostAdvise(long word word) DdePostAdvise16
 14 pascal DdeCreateDataHandle(long ptr long long word word word) DdeCreateDataHandle16
 15 pascal DdeAddData(word ptr long long) DdeAddData16
@@ -22,7 +22,7 @@
 23 pascal DdeQueryString (long word ptr long word) DdeQueryString16
 24 pascal -ret16 DdeKeepStringHandle(long long) DdeKeepStringHandle16
 
-26 pascal -ret16 DdeEnableCallback(long word word) DdeEnableCallback16
+26 pascal -ret16 DdeEnableCallback(long long word) DdeEnableCallback16
 27 pascal DdeNameService(long long long s_word) DdeNameService16
 
 36 pascal -ret16 DdeCmpStringHandles(word word) DdeCmpStringHandles16