devnam

    OpenVMS usage:char_string
    type:         character string
    access:       read only
    mechanism:    by descriptor
    Name of the device on which the volume is physically mounted. The
    descriptor must point to the device name, a character string of 1
    to 64 characters. The device name can be a physical device name
    or a logical name; if it is a logical name, it must translate to
    a physical name.

    The device does not have to be currently allocated; however,
    allocating the device before initializing it is recommended.

 volnam

    OpenVMS usage:char_string
    type:         character string
    access:       read only
    mechanism:    by descriptor
    Identification to be encoded on the volume. The descriptor
    must point to the volume name, a character string of 1 to 12
    characters. For a disk volume name, you can specify a maximum
    of 12 ANSI characters; for a magnetic tape volume name, you can
    specify a maximum of 6 ANSI "a" characters.

    Any valid ANSI "a" characters can be used; these include numbers,
    uppercase letters, and any one of the following nonalphanumeric
    characters:

    ! " % ' ( ) * + , - . / : ; < = >

    VSI strongly recommends that a disk volume name consist of only
    alphanumeric characters, dollar signs ($),  underscores (_), and
    hyphens (-).

 itmlst

    OpenVMS usage:item_list_3
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    Item list specifying options that can be used when initializing
    the volume. The itmlst argument is the address of a list of item
    descriptors, each of which describes one option. The list of item
    descriptors is terminated by a longword of 0.

    To view the item code diagram and descriptor fields table, see
    the VSI OpenVMS System Services Reference Manual.