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

    (Alpha only) Causes the debugger to break directly after any
    instruction that accesses unaligned data (for example, after a
    load word instruction that accesses data that is not on a word
    boundary).