`ox_select'
-----------

ox_select(NLIST[,TIMEOUT])
     :: Returns the list of process identifiers on which data is
     available.

RETURN
     list

NLIST
     list of integers (process identifier)

TIMEOUT
     number

   * Returns the list of process identifiers on which data is available.

   * If all the processes in NLIST are running, it blocks until one of
     the processes returns data. If TIMEOUT is specified, it waits for
     only TIMEOUT seconds.

   * By sending `SM_popCMO' or `SM_popSerializedLocalObject' with
     `ox_push_cmd()' in advance and by examining the process status with
     `ox_select()', one can avoid a hanging up caused by
     `ox_pop_local()' or `ox_pop_cmo()'. In such a case, data can be
     received by `ox_get()'.

     ox_launch();
     0
     [220] ox_launch();
     1
     [221] ox_launch();
     2
     [222] ox_rpc(2,"fctr",x^500-y^500);
     0
     [223] ox_rpc(1,"fctr",x^100-y^100);
     0
     [224] ox_rpc(0,"fctr",x^10-y^10);
     0
     [225] P=[0,1,2];
     [0,1,2]
     [226] map(ox_push_cmd,P,258);
     [0,0,0]
     [227] ox_select(P);
     [0]
     [228] ox_get(0);
     [[1,1],[x^4+y*x^3+y^2*x^2+y^3*x+y^4,1],
     [x^4-y*x^3+y^2*x^2-y^3*x+y^4,1],[x-y,1],[x+y,1]]

References
     *Note `ox_pop_cmo ox_pop_local': ox_pop_cmo ox_pop_local, *Note
     `ox_push_cmd ox_sync': ox_push_cmd ox_sync, *Note `ox_get': ox_get

