Given a property-set of the form
        v1/v2/...vN-1/<fN>vN/<fN+1>vN+1/...<fM>vM

    Returns
        v1 v2 ... vN-1 <fN>vN <fN+1>vN+1 ... <fM>vM

    Note that vN...vM may contain slashes. This is resilient to the
    substitution of backslashes for slashes, since Jam, unbidden,
    sometimes swaps slash direction on NT.

def split (properties):
    """ Given a property-set of the form
        v1/v2/...vN-1/<fN>vN/<fN+1>vN+1/...<fM>vM

    Returns
        v1 v2 ... vN-1 <fN>vN <fN+1>vN+1 ... <fM>vM

    Note that vN...vM may contain slashes. This is resilient to the
    substitution of backslashes for slashes, since Jam, unbidden,
    sometimes swaps slash direction on NT.
    """
    assert isinstance(properties, basestring)
    def split_one (properties):
        pieces = re.split (__re_slash_or_backslash, properties)
        result = []

        for x in pieces:
            if not get_grist (x) and len (result) > 0 and get_grist (result [-1]):
                result = result [0:-1] + [ result [-1] + '/' + x ]
            else:
                result.append (x)

        return result

    if isinstance (properties, str):
        return split_one (properties)

    result = []
    for p in properties:
        result += split_one (p)
    return result