def get_markings(obj):
    """
    Get all object level markings from the given SDO or SRO object.

    Args:
        obj: A SDO or SRO object.

    Returns:
        list: Marking identifiers contained in the SDO or SRO. Empty list if no
            markings are present in `object_marking_refs`.

    """
    return obj.get('object_marking_refs', [])
