Selecting _id does not work

[sirex]

Example where it does not work: https://get.data.gov.lt/datasets/gov/lst/standards/ICS?select(_id,notation)

This gives:

Traceback (most recent call last):
  File "spinta/api.py", line 91, in homepage
    return await create_http_response(context, params, request)
  File "spinta/utils/response.py", line 165, in create_http_response
    return await commands.getall(
  File "spinta/commands/read.py", line 95, in getall
    return render(context, request, model, params, rows, action=action)
  File "spinta/renderer.py", line 22, in render
    return commands.render(
  File "spinta/formats/html/commands.py", line 129, in render
    return _render_model(context, request, model, action, params, data, headers)
  File "spinta/formats/html/commands.py", line 210, in _render_model
    header = _get_model_tabular_header(context, model, action, params)
  File "spinta/formats/html/commands.py", line 189, in _get_model_tabular_header
    return get_model_tabular_header(
  File "spinta/formats/helpers.py", line 92, in get_model_tabular_header
    names = get_select_prop_names(
  File "spinta/backends/helpers.py", line 93, in get_select_prop_names
    check_unknown_props(model, select, known)
  File "spinta/backends/helpers.py", line 251, in check_unknown_props
    raise exceptions.MultipleErrors(
spinta.exceptions.MultipleErrors: Multiple errors:
 - Unknown property '_id'.
     Context:
       component: spinta.components.Model
       manifest: default
       schema: 4997
       dataset: datasets/gov/lst/standards
       model: datasets/gov/lst/standards/ICS
       entity:
       property: _id