def METHOD_NAME(field):
    """Return a list of diff map characters for a field."""
    lines = field.split("\n")
    diffmap = []
    inmap = False
    for line in lines:
        if "1234567890" in line or re.search(r"^\s*\d+\s*$", line):
            inmap = True
        if r"->" in line and inmap:
            mapline = re.sub(r".*->", r"", line)
            diffmap += list(mapline)
    return diffmap