/sys$common/syshlp/helplib.hlb Sys Parameters, WBM_OPCOM_LVL  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    WBM_OPCOM_LVL controls whether write bitmap system messages are
    sent to the operator console. Possible values are shown in the
    following table:

    Value Description

    0     Messages are turned off.
    1     The default; messages are provided when write bitmaps are
          started, deleted, and renamed, and when the SCS message
          mode (buffered or single) changes.
    2     All messages for a setting of 1 are provided plus many
          more.

    WBM_OPCOM_LVL is a DYNAMIC parameter.