VMS Help System Services, $IEEE SET FP CONTROL (Alpha Only), Arguments  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 clrmsk

    OpenVMS usage:mask_quadword
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by reference
    Address of a quadword bit mask to be cleared in the IEEE
    floating-point control register.

    The $IEEEDEF macro defines symbols for the floating-point
    control register. The following table shows the symbols, their
    corresponding masks, and their meaning:

    Table SYS-4 Format of the IEEE Floating-Point Control Register
                (Alpha Only)

    Symbol                 Mask    Meaning

    IEEE$M_TRAP_ENABLE_    2       Invalid operation
    INV
    IEEE$M_TRAP_ENABLE_    4       Divide by 0
    DZE
    IEEE$M_TRAP_ENABLE_    8       Overflow
    OVF
    IEEE$M_TRAP_ENABLE_    10      Underflow
    UNF
    IEEE$M_TRAP_ENABLE_    20      Inexact
    INE
    IEEE$M_MAP_UMZ         4000    Underflows are mapped to 0.0
    IEEE$M_INHERIT         8000    Inherit FP state on thread create
    IEEE$M_STATUS_INV      20000   Invalid operation
    IEEE$M_STATUS_DZE      40000   Divide by 0
    IEEE$M_STATUS_OVF      80000   Overflow
    IEEE$M_STATUS_UNF      100000  Underflow
    IEEE$M_STATUS_INE      200000  Inexact

 setmsk

    OpenVMS usage:mask_quadword
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by reference
    Address of a quadword bit mask to be set in the IEEE floating-
    point control register.

    See the clrmsk argument for the format of the IEEE floating-point
    control register.

 prvmsk

    OpenVMS usage:mask_quadword
    type:         quadword (unsigned)
    access:       write only
    mechanism:    by reference
    Address of a quadword to receive the previous value of the IEEE
    floating-point control register.