region_id_64

    OpenVMS usage:region identifier
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by 32- or 64-bit reference
    The region ID associated with the region from which to address
    the VA space.

    The file VADEF.H in SYS$STARLET_C.TLB and the $VADEF macro in
    STARLET.MLB define a symbolic name for each of the three default
    regions in P0, P1, and P2 space.

    The following region IDs are defined:

    Symbol     Region

    VA$C_P0    Program region
    VA$C_P1    Control region
    VA$C_P2    64-bit program region

    Other region IDs, as returned by the $CREATE_REGION_64 service,
    can be specified. Also, the region ID that a virtual address
    is in can be obtained by calling the $GET_REGION_INFO service,
    specifying the VA$_REGSUM_BY_VA function.

 start_va_64

    OpenVMS usage:address
    type:         quadword address
    access:       read only
    mechanism:    by value
    The starting virtual address of the pages to be deleted. The
    specified address must be a CPU-specific page aligned address.
    If the region_id_64 argument specifies a shared page table region
    or if the start_va_64 argument lies within a shared page table
    region, the specified address must be a CPU-specific page table
    page aligned address.

 length_64

    OpenVMS usage:byte count
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by value
    Length of the virtual address space to be deleted. The length
    specified must be a multiple of CPU-specific pages. If the
    virtual address space is being deleted from a shared page table
    region, the specified length must be page table page aligned or
    include the last page in a memory-resident section.

 acmode

    OpenVMS usage:access_mode
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Access mode associated with the call to $DELTVA_64. The acmode
    argument is a longword containing the access mode.

    The $PSLDEF macro in STARLET.MLB and the file PSLDEF.H in
    SYS$STARLET_C.TLB define the following symbols and their values
    for the four access modes:

    Value      Symbolic Name      Access Mode

    0          PSL$C_KERNEL       Kernel
    1          PSL$C_EXEC         Executive
    2          PSL$C_SUPER        Supervisor
    3          PSL$C_USER         User

    The most privileged access mode used is the access mode of the
    caller. The calling process can delete pages only if those pages
    are owned by an access mode equal to or less privileged than the
    access mode of the calling process.

 return_va_64

    OpenVMS usage:address
    type:         quadword address
    access:       write only
    mechanism:    by 32- or 64-bit reference
    The lowest process virtual address of the deleted virtual address
    range. The return_va_64 argument is the 32- or 64-bit virtual
    address of a naturally aligned quadword into which the $DELTVA_64
    service returns the virtual address.

 return_length_64

    OpenVMS usage:byte count
    type:         quadword (unsigned)
    access:       write only
    mechanism:    by 32- or 64-bit reference
    The 32- or 64-bit virtual address of a naturally aligned quadword
    into which the $DELTVA_64 service returns the length in bytes of
    the virtual address range deleted.