Library /sys$common/syshlp/dtehelp.hlb SET, DTE, /BREAK  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /BREAK=break-character

    Selects the break character. The break character is used to
    generate a break on lines that expect a break rather than a
    carriage return. To generate a break, press CTRL/break-character.

    You can select the break character from 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
    command character (see the /COMMAND Subtopic) or the escape
    character (see the /ESCAPE Subtopic).

    By default, the break character is the right bracket (]).