def _is_sld(model_info, id):
    """
    Return True if parameter is a magnetic magnitude or SLD parameter.
    """
    if id.startswith('M0:'):
        return True
    if '_pd' in id or '.' in id:
        return False
    for p in model_info.parameters.call_parameters:
        if p.id == id:
            return p.type == 'sld'
    # check through kernel parameters in case it is a named as a vector
    for p in model_info.parameters.kernel_parameters:
        if p.id == id:
            return p.type == 'sld'
    return False