def is_fork_split(mp):
    """Returns true if the fork was split into two parts and false if not.

    Parameters
    ----------
    mp : dictionary
        The measured data.

    Returns
    -------
    forkIsSplit : boolean

    """
    forkIsSplit = False
    for key in mp.keys():
        if key[:1] == 'S' or key[1:2] == 'S':
            forkIsSplit = True
    return forkIsSplit
