/sys$common/syshlp/helplib.hlb SET, HOST, /DTE, Qualifiers, /ESCAPE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /ESCAPE=escape-character

    Selects the escape character. You can use the escape character to
    exit from DTEPAD by pressing Ctrl/ escape-character.

    The escape character can be any ASCII character between @ and z,
    except C, M, Q, S, Y, or the left bracket ([).  You cannot select
    a character currently defined as either the break character (see
    the description of the /BREAK=break-character qualifier) or the
    command character (see the description of the /COMMAND=command-
    character qualifier).

    By default, the escape character is a backslash (\).

    The ASCII characters between @ and z include the alphabetic
    characters in both upper and lower cases, the at sign (@),  the
    backslash (\),  the right bracket (]), the circumflex (^),  the
    underscore (_),  and the grave accent (`).