Types:
    - nativ datatypes: string, number, boolean, JSON
    - HTML: string with HTML content
    - float: numbers that are expected to be non-integer. Formatted as in rfc7159.
    - decimal(X): Decimal values represented as a string with X decimal places
    - datetime: Datetime as a unix timestamp. Why a number? This enables queries
      in the DB. And we do not need more precision than 1 second.
Relations:
    - <collection>/<field>: This is a reference to a collection. The reverse relation
      field is <field>. E.g. `category_id: motion_category/motion_ids` in a motion links
      to one category. The reverse field is `motion_ids` which may be `motion_ids:
      (motion/category_id)[]` indicating, that there are many motion ids.
    - <T>[]: This indicated multiple ids. For an example see above.
    - */<field>: This is a generic relation (analog: `(*/<field>)[]` a generic
      list relation) with fqids as values.
    - If no field is specified, there is no reverse relation.
Structured Fields:
    - There are template fields (see autoupdate service interface) with a `$` as
      the placeholder. In this document, angle brackets are followed by the
      dollar sign including the meaning of the template. E.g.
      group_$<meeting_id>_ids: (group/user_ids)[];
      says, that the template are meeting ids and each structured field is a
      multi-relation to groups and the reverse relation field for groups is
      user_ids.

Interface organisation {
    id: number;
    name: string;
    description: HTML;

    // Configs
    legal_notice: string;
    privacy_policy: string;
    login_text: string;
    theme: string;
    custom_translations: JSON;

    committee_ids: (committee/organisation_id)[];
    role_ids: (role/organisation_id)[];
    superadmin_role_id: role/superadmin_role_for_organisation_id;
    resource_ids: (resource/organisation_id)[];
}

Interface user {
    id: number;
    username: string;
    title: string;
    first_name: string;
    last_name: string;
    is_active: boolean;
    is_committee: boolean;
    password: string;
    default_password: string;
    about_me: HTML;
    gender: string;
    comment: HTML;
    number: string;
    structure_level: string;
    email: string;
    last_email_send: string;
    vote_weight: decimal;

    role_id: role/user_ids; // Attention: prevent impelenting a "default-role" or let a
    // user create such a role! This would cause the user_ids-array for this
    // role to explode in size. If a user has no role, it should be handles as
    // the user has no permission in the organisation and is a "normal" delegate
    // there. Just a few users (expected <100) should even get a role and all
    // other don't.

    // Meeting and committee
    is_present_in_meeting_ids: (meeting/present_user_ids)[];
    meeting_id: meeting/temporary_user_ids;  // Temporary users
    guest_meeting_ids: (meeting/guest_ids)[];  // Guests in meetings
    committee_as_member_ids: (committee/member_ids)[];
    committee_as_manager_ids: (committee/manager_ids)[];

    // Projection
    projection_ids: (projection/element_id)[];
    current_projector_ids: (projector/current_element_ids)[]

    // All foreign keys are meeting-specific:
    // - Keys are smaller (Space is in O(n^2) for n keys
    //   in the relation), so this saves storagespace
    // - This makes quering things like this possible:
    //   "Give me all groups for User X in Meeting Y" without
    //   the need to get all groups and filter them for the meeting
    group_$<meeting_id>_ids: (group/user_ids)[];
    speaker_$<meeting_id>_ids: (speaker/user_id)[];
    personal_note_$<meeting_id>_ids: (personal_note/user_id)[];
    supported_motion_$<meeting_id>_ids: (motion/supporter_ids)[];
    submitted_motion_$<meeting_id>_ids: (motion_submitter/user_id)[];
    motion_poll_voted_$<meeting_id>_ids: (motion_poll/voted_ids)[];
    motion_vote_$<meeting_id>_ids: (motion_vote/user_id)[];
    assignment_candidate_$<meeting_id>_ids: (assignment_candidate/user_id)[];
    assignment_poll_voted_$<meeting_id>_ids: (assignment_poll/voted_ids)[];
    assignment_option_$<meeting_id>_ids: (assignment_option/user_id)[];
    assignment_vote_$<meeting_id>_ids: (assignment_vote/user_id)[];
}

Interface role {
    id: number;
    name: string;
    permissions: string[];

    organisation_id: organisation/role_ids;
    superadmin_role_for_organisation_id: organisation/superadmin_role_id;
    user_ids: (user/role_id)[];
}

// New: Resource
// Resources are organsation wide "mediafiles", like logos for the organisatio or
// organisation-wide fonts. Therefore, no permission checks are done and the user
// must not be logged in to retrieve files. A resource has a token, e.g. `web_header`
// or `pdf_font_italic`, so the client knowns, where to put the resource.
Interface resource {
    id: number;
    token: string;
    filesize: number;
    mimetype: string;

    organisation_id: organisation/resource_ids;
}

Interface committee {
    id: number;
    name: string;
    description: HTML;

    meeting_ids: (meeting/committee_id)[];
    default_meeting_id: meeting/default_meeting_for_committee_id;
    member_ids: (user/committee_as_memeber_ids)[];
    manager_ids: (user/committee_as_manager_ids)[];
    forward_to_committee_ids: (committee/receive_forwardings_from_committee_ids)[];
    receive_forwardings_from_committee_ids: (committee/forward_to_committee_ids)[];
    organisation_id: organisation/committee_ids;
}

Interface meeting {
    id: number;
    welcome_title: string;
    welcome_text: HTML;

    // General
    name: string;
    description: string;
    location: string;
    start_time: datetime;
    end_time: datetime; // TODO: is this needed?
    custom_translations: JSON;

    // System
    url_name: string; // For unique urls.
    is_template: boolean; // Unique within a committee
    enable_anonymous: boolean;

    // Jitsi/Livestream settings
    conference_show: boolean: boolean;
    conference_auto_connect: boolean;
    conference_los_restriction: boolean;
    conference_stream_url: string;

    // Projector
    projector_default_countdown_time: number;
    projector_countdown_warning_time: number;

    // Exports
    export_csv_encoding: string;
    export_csv_separator: string;
    export_pdf_pagenumber_alignment: string;
    export_pdf_fontsize: number;
    export_pdf_pagesize: string;

    // Agenda
    agenda_show_subtitles: boolean;
    agenda_enable_numbering: boolean;
    agenda_number_prefix: string;
    agenda_numeral_system: string;
    agenda_item_creation: string;
    agenda_new_items_default_visibility: number;
    agenda_show_internal_items_on_projector: boolean;

    // List of speakers
    list_of_speakers_amount_last_on_projector: number;
    list_of_speakers_amount_next_on_projector: boolean;
    list_of_speakers_couple_countdown: boolean;
    list_of_speakers_show_amount_of_speakers_on_slide: boolean;
    list_of_speakers_present_users_only: boolean;
    list_of_speakers_show_first_contribution: boolean;

    // Motions
    motions_default_workflow_id: workflow/default_workflow_meeting_id;
    motions_default_statute_amendments_workflow_id: workflow/default_statute_amendments_meeting_id;
    motions_preamble: string;
    motions_default_line_numbering: string;
    motions_line_length: number;
    motions_reason_required: boolean;
    motions_enable_text_on_projector: boolean;
    motions_enable_reason_on_projector: boolean;
    motions_enable_sidebox_on_projector: boolean;
    motions_enable_recommendation_on_projector: boolean;
    motions_show_referring_motions: boolean;
    motions_show_sequential_number: boolean;
    motions_recommendations_by: string;
    motions_statute_recommendations_by: string;
    motions_recommendation_text_mode: string;
    motions_default_sorting: string;
    motions_identifier_type: string;
    motions_identifier_min_digits: number;
    motions_identifier_with_blank: boolean;
    motions_statutes_enabled: boolean;
    motions_amendments_enabled: boolean;
    motions_amendments_in_main_list: boolean;
    motions_amendments_of_amendments: boolean;
    motions_amendments_prefix: string;
    motions_amendments_text_mode: string;
    motions_amendments_multiple_paragraphs: boolean;
    motions_supporters_min_amount: number;
    motions_supporters_enable_autoremove: boolean;
    motions_export_title: string;
    motions_export_preamble: string;
    motions_export_submitter_recommendation: boolean;
    motions_export_follow_recommendation: boolean;

    motion_poll_ballot_paper_selection: string;
    motion_poll_ballot_paper_number: number;
    motion_poll_default_type: string;
    motion_poll_default_100_percent_base: string;
    motion_poll_default_majority_method: string;
    motion_poll_default_group_ids: (group/used_as_motion_poll_default_id)[];

    // Users
    users_sort_by: string;
    users_enable_presence_view: boolean;
    users_enable_vote_weight: boolean;
    users_allow_self_set_present: boolean;
    users_pdf_welcometitle: string;
    users_pdf_welcometext: string;
    users_pdf_url: string;
    users_pdf_wlan_ssid: string;
    users_pdf_wlan_password: string;
    users_pdf_wlan_encryption: string;
    users_email_sender: string;
    users_email_replyto: string;
    users_email_subject: string;
    users_email_body: string;

    // Assignments
    assignemnts_export_title: string;
    assignments_export_preamble: string;
    assignment_poll_add_candidates_to_list_of_speakers: boolean;
    assignment_poll_sort_poll_result_by_votes: boolean;
    assignment_poll_default_type: string;
    assignment_poll_default_method: string;
    assignment_poll_default_100_percent_base: string;
    assignment_poll_default_majority_method: string;
    assignment_poll_default_group_ids: (group/used_as_assignment_poll_default_id)[];

    projector_ids: (projector/meeting_id)[];
    projectiondefault_ids: (projectiondefault/meeting_id)[];
    projector_message_ids: (projector_message/meeting_id)[];
    projector_countdown_ids: (projector_countdown/meeting_id)[];
    tag_ids: (tag/meeting_id)[];
    agenda_item_ids: (agenda_item/meeting_id)[];
    list_of_speakers_ids: (list_of_speakers/meeting_id)[];
    topic_ids: (topic/meeting_id)[];
    group_ids: (group/meeting_id)[];
    mediafile_ids: (mediafile/meeting_id)[];
    motion_ids: (motion/meeting_id)[];
    motion_comment_section_ids: (motion_comment_section/meeting_id)[];
    motion_category_ids: (motion_category/meeting_id)[];
    motion_block_ids: (motion_block/meeting_id)[];
    motion_workflow_ids: (motion_workflow/meeting_id)[];
    motion_statute_paragraph_ids: (motion_statute_paragraph/meeting_id)[];
    motion_poll_ids: (motion_poll/meeting_id)[];
    assignment_ids: (assignment/meeting_id)[];
    assignment_poll_ids: (assignment_poll/meeting_id)[];

    // No relations to a meeting:
    // user; OK, because not meeting-specific
    // personal_note
    // projection
    // speaker
    // motion_option
    // motion_vote
    // motion_comment
    // motion_submitter
    // motion_change_recommendation
    // motion_state
    // assignment_candidate
    // assignment_option
    // assignment_vote

    // Logos and Fonts
    logo_$<token>: mediafile/used_as_logo_$<token>_in_meeting;
    font_$<token>: mediafile/used_as_font_$<token>_in_mmeting;
    // Examples:
    // logo_web_header: Mediafile;
    // font_italic_pdf: Mediafile;
    // The client can define these resources. There is no need
    // to have whitelist/blacklist on the server. The tokens must
    // be checked: They must match `[a-z]([a-z_]*[a-z])?` and must
    // not be longer than 32 characters.

    // Other relations
    committee_id: committee/meeting_ids;
    default_meeting_for_committee_id: committee/default_meeting_id;
    present_user_ids: (user/is_present_in_meeting_ids)[];
    temporary_user_ids: (user/meeting_id)[];
    guest_ids: (user/guest_meeting_ids)[];
    user_ids: (Id)[]; // Calculated: All ids from temporary_user_ids, guest_ids and all users assigned to groups.
    reference_projector_id: projector/used_as_reference_projector_meeting_id;

    default_group_id: group/default_group_for_meeting_id;
    superadmin_group_id: group/superadmin_group_for_meeting_id;
}

Interface group {
    id: number;
    name: string;
    permissions: string[];

    user_ids: (user/group_$<meeting_id>_ids)[];
    default_group_for_meeting_id: meeting/default_group_id;
    superadmin_group_for_meeting_id: meeting/superadmin_group_id;
    mediafile_access_group_ids: (mediafile/access_group_ids)[];
    mediafile_inherited_access_group_ids: (mediafile/inherited_access_group_ids)[];
    read_comment_section_ids: (motion_comment_section/read_group_ids)[];
    write_comment_section_ids: (motion_comment_section/write_group_ids)[];
    motion_poll_ids: (motion_poll/entitled_group_ids)[];
    assignment_poll_ids: (assignment_poll/entitled_group_ids)[];
    used_as_motion_poll_default_id: meeting/motion_poll_default_group_ids;
    used_as_assignment_poll_default_id: meeting/assignment_poll_default_group_ids;
    meeting_id: meeting/group_ids;
}

Interface personal_note {
    id: number;
    note: HTML;
    star: boolean;

    user_id: user/personal_note_$<meeting_id>_ids;
    content_object_id: */personal_note_ids;
}

Interface tag {
    id: number;
    name: string;

    tagged_ids: (*/tag_ids)[];
    meeting_id: meeting/tag_ids;
}

Interface agenda_item {
    id: number;
    item_number: string;
    comment: string;
    closed: boolean;
    type: number;
    is_internal: boolean;
    is_hidden: boolean;
    duration: number; // in seconds
    weight: number;
    level: number; // calculated.

    content_object_id: */agenda_item_id;
    parent_id: agenda_item/child_ids;
    child_ids: (agenda_item/parent_id)[];
    tag_ids: (tag/tagged_ids)[];
    projection_ids: (projection/element_id)[];
    current_projector_ids: (projector/current_element_ids)[];
    meeting_id: meeting/agenda_item_ids;
}

Interface list_of_speakers {
    id: number;
    closed: boolean;

    content_object_id: */list_of_speakers_id;
    speaker_ids: (speaker/list_of_speakers_id)[];
    projection_ids: (projection/element_id)[];
    current_projector_ids: (projector/current_element_ids)[];
    meeting_id: meeting/list_of_speakers_ids;
}

Interface speaker {
    id: number;
    begin_time: datetime;
    end_time: datetime;
    weight: number;
    marked: boolean;

    list_of_speakers_id: list_of_speakers/speaker_ids;
    user_id: user/speaker_$<meeting_id>_ids;
}

Interface topic {
    id: number;
    title: string;
    text: HTML;

    attachment_ids: (mediafile/attachement_ids)[];
    agenda_item_id: agenda_item/content_object_id;
    list_of_speakers_id: list_of_speakers/content_object_id;
    tag_ids: (tag/tagged_ids)[];
    meeting_id: meeting/topic_ids;
}

Interface motion {
    id: number;
    number: string;
    sequential_number: number;
    title: string;
    text: HTML;
    amendment_paragraph_$<paragraph_number>: HTML;
    modified_final_version: HTML;
    reason: HTML;
    category_weight: number;
    state_extension: string;
    recommendation_extension: string;
    sort_weight: number;
    created: datetime;
    last_modified: datetime;

    lead_motion_id: motion/amendment_ids;
    amendment_ids: (motion/lead_motion_id)[];
    sort_parent_id: motion/sort_child_ids;
    sort_child_ids: (motion/parent_id)[];
    origin_id: motion/derived_motion_ids; // Note: The related motions may not be in the same meeting
    derived_motion_ids: (motion/origin_id)[]; // Note: The related motions may not be in the same meeting
    forwarding_tree_motion_ids: (Id)[]; // Calculated: All children (derived_motion_ids), grand children, ... and all parents (origin_id).
    state_id: motion_state/motion_ids;
    recommendation_id: motion_state/motion_recommendation_ids;
    recommendation_extension_reference_ids: (*/referenced_in_motion_recommendation_extension_ids)[]; // current option: motion
    referenced_in_motion_recommendation_extension_ids: (motion/recommendation_extension_reference_ids)[];
    category_id: motion_category/motion_ids;
    block_id: motion_block/motion_ids;
    submitter_ids: (motion_submitter/motion_id)[];
    supporter_ids: (user/supported_motion_$<meeting_id>_ids)[];
    poll_ids: (motion_poll/motion_id)[];
    change_recommendation_ids: (motion_change_recommendation/motion_id)[];
    statute_paragraph_id: motion_statute_paragraph/motion_ids;
    comment_ids: (motion_comment/motion_id)[];
    agenda_item_id: agenda_item/content_object_id;
    list_of_speakers_id: list_of_speakers/content_object_id;
    tag_ids: (tag/tagged_ids)[];
    attachment_ids: (mediafile/attachment_ids)[];
    projection_ids: (projection/element_id)[];
    current_projector_ids: (projector/current_element_ids)[];
    personal_note_ids: (personal_note/content_object_id)[];
    meeting_id: meeting/motion_ids;
}

Interface motion_submitter {
    id: number;
    weight: number;

    user_id: user/submitted_motion_$<meeting_id>_ids;
    motion_id: motion/submitter_ids;
}

Interface motion_comment {
    id: number;
    comment: HTML;

    motion_id: motion/comment_ids;
    section_id: motion_comment_section/comment_ids;
}

Inteface motion_comment_section {
    id: number;
    name: string;
    weight: number;

    comment_ids: (motion_comment/section_id)[];
    read_group_ids: (group/read_comment_section_ids)[];
    write_group_ids: (group/write_comment_section_ids)[];
    meeting_id: meeting/motion_comment_section_ids;
}

Interface motion_category {
    id: number;
    name: string;
    prefix: string;
    weight: number;
    level: number;

    parent_id: motion_category/child_ids;
    child_ids: (motion_category/parent_id)[];
    motion_ids: (motion/category_id)[];
    meeting_id: meeting/category_ids;
}

Interface motion_block {
    id: number;
    title: string;
    internal: boolean;

    motion_ids: (motion/block_id)[];
    agenda_item_id: agenda_item/content_object_id;
    list_of_speakers_id: list_of_speakers/content_object_id;
    projection_ids: (projection/element_id)[];
    current_projector_ids: (projector/current_element_ids)[];
    meeting_id: meeting/motion_block_ids;
}

Interface motion_change_recommendation {
    id: number;
    rejected: boolean;
    internal: boolean;
    type: number;
    other_description: string;
    line_from: number;
    line_to: number;
    text: HTML;
    creation_time: datetime;

    motion_id: motion/change_recommendation_ids;
}

Interface motion_state {
    id: number;
    name: string;
    recommendation_label: string;
    css_class: string;
    restrictions: string[];
    allow_support: boolean;
    allow_create_poll: boolean;
    allow_submitter_edit: boolean;
    set_number: boolean;
    show_state_extension_field: boolean;
    merge_amendment_into_final: number;
    show_recommendation_extension_field: boolean;

    next_state_ids: (motion_state/previous_state_ids)[];
    previous_state_ids: (motion_state/next_state_ids)[];
    motion_ids: (motion/state_id)[];
    motion_recommendation_ids: (motion/recommendation_id)[];
    workflow_id: motion_workflow/state_ids;
    first_state_of_workflow_id: motion_workflow/first_state_id;
}

Interface motion_workflow {
    id: number;
    name: string;

    state_ids: (motion_state/workflow_id)[];
    first_state_id: motion_state/first_state_of_workflow_id;
    default_workflow_meeting_id: meeting/motions_default_workflow_id;
    default_statute_amendments_meeting_id: meeting/motions_default_statute_amendments_workflow_id;
    meeting_id: meeting/motion_workflow_ids;
}

Interface motion_statute_paragraph {
    id: number;
    title: string;
    text: HTML;
    weight: number;

    motion_ids: (motion/statute_paragraph_id)[];
    meeting_id: meeting/motion_statute_paragraph_ids;
}

Interface motion_poll {
    id: number;
    pollmethod: string;
    state: number;
    type: string;
    title: string;
    onehundred_percent_base: string;
    majority_method: string;
    votesvalid: decimal(6);
    votesinvalid: decimal(6);
    votescast: decimal(6);
    user_has_voted: boolean; // This is user specific and set during restriction

    motion_id: motion/poll_ids;
    option_ids: (motion_option/poll_id)[];
    voted_ids: (user/motion_poll_voted_$<meeting_id>_ids)[];
    entitled_group_ids: (group/motion_poll_ids)[];
    projection_ids: (projection/element_id)[];
    current_projector_ids: (projector/current_element_ids)[];
    meeting_id: meeting/motion_poll_ids;
}

Interface motion_option {
    id: number;
    yes: decimal(6);
    no: decimal(6);
    abstain: decimal(6);

    poll_id: motion_poll/option_ids;
    vote_ids: (motion_vote/option_id)[];
}

Interface motion_vote {
    id: number;
    weight: decimal(6);
    value: string;

    option_id: motion_option/vote_ids;
    user_id: user/motion_vote_$<meeting_id>_ids;
}

Interface assignment {
    id: number;
    title: string;
    description: HTML;
    open_posts: number;
    phase: number;
    default_poll_description: string;
    number_poll_candidates: boolean;

    candidate_ids: (assignment_candidate/assignment_id)[];
    poll_ids: (assignment_poll/assignment_id)[];
    agenda_item_id: agenda_item/content_object_id;
    list_of_speakers_id: list_of_speakers/content_object_id;
    tag_ids: (tag/tagged_ids)[];
    attachment_ids: (mediafile/attachment_ids)[];
    projection_ids: (projection/element_id)[];
    current_projector_ids: (projector/current_element_ids)[];
    meeting_id: meeting/assignment_ids;
}

Inteface assignment_candidate {
    id: number;
    weight: number;

    assignment_id: assignment/candidate_ids;
    user_id: user/assignment_candidate_$<meeting_id>_ids;
}

Interface assignment_poll {
    id: number;
    description: string;
    pollmethod: string;
    votes_amount: number;
    allow_multiple_votes_per_candidate: boolean;
    global_abstain: boolean;
    global_no: boolean;
    amount_global_abstain: decimal(6);
    amount_global_no: decimal(6);
    state: number;
    title: string;
    type: string;
    onehundred_percent_base: string;
    majority_method: string;
    votescast: decimal(6);
    votesinvalid: decimal(6);
    votesvalid: decimal(6);
    user_has_voted: boolean; // This is user specific and set during restriction

    assignment_id: assignment/poll_ids;
    voted_ids: (user/assignment_poll_voted_$<meeting_id>_ids)[];
    entitled_group_ids: (group/assignment_poll_ids)[];
    option_ids: (assignment_option/poll_id)[];
    projection_ids: (projection/element_id)[];
    current_projector_ids: (projector/current_element_ids)[];
    meeting_id: meeting/assignment_poll_ids;
}

Interface assignment_option {
    id: number;
    yes: decimal(6);
    no: decimal(6);
    abstain: decimal(6);
    weight: number;

    poll_id: assignment_poll/option_ids;
    user_id: user/assignment_option_$<meeting_id>_ids;
    vote_ids: (assignment_vote/option_id)[];
}

Interface assignment_vote {
    id: number;
    value: string;
    weight: decimal(6);

    option_id: assignment_option/vote_ids;
    user_id: user/assignment_vote_$<meeting_id>_ids;
}

// Mediafiles are delivered by the mediafile server with the URL
// `<media-prefix>/media/<meeting_id>/path`
Interface mediafile {
    id: number;
    title: string;
    is_directory: boolean;
    filesize: number; // Note: in bytes, not the human readable format anymore
    filename: string; // Note: The uploaded filename. Filename and parent_id
    // must be unique as well as title and parent_id must be unique.
    mimetype: string;
    pdf_information: JSON;
    create_timestamp: datetime;
    path: string; // Note: calculated
    has_inherited_access_groups: boolean; // Note: calculated

    inherited_access_group_ids: (group/mediafile_inherited_access_group_ids)[];  // Note: calculated
    access_group_ids: (group/mediafile_access_group_ids)[];
    parent_id: mediafile/child_ids;
    child_ids: (mediafile/parent_id)[];
    list_of_speakers_id: list_of_speakers/content_object_id;
    projection_ids: (projection/element_id)[];
    current_projector_ids: (projector/current_element_ids)[];
    attachment_ids: (*/attachment_ids)[];
    meeting_id: meeting/mediafile_ids;

    // Reverse relations for meetings, if a mediafile is used as a special resource
    used_as_logo_$<token>_in_meeting: meeting/logo_$<token>;
    used_as_font_$<token>_in_meeting: meeting/font_$<token>;
}

Interface projector {
    id: number;
    name: string;
    scale: number;
    scroll: number;
    width: number;
    aspect_ratio_numerator: number;
    aspect_ratio_denominator: number;
    color: string;
    background_color: string;
    header_background_color: string;
    header_font_color: string;
    header_h1_color: string;
    chyron_background_color: string;
    chyron_font_color: string;
    show_header_footer: boolean;
    show_title: boolean;
    show_logo: boolean

    current_projection_ids: (projection/current_projector_id)[];
    // A relation to the currently projected elements to get a direct link, if
    // the element is projected.
    current_element_ids: (*/current_projector_ids)[];
    preview_projection_ids: (projection/projector_preview_id)[];
    history_projection_ids: (projection/projector_history_id)[];
    used_as_reference_projector_meeting_id: meeting/reference_projector_id;
    projectiondefault_ids: (projectiondefault/projector_id)[];
    meeting_id: meeting/projector_ids;
}

// A projection is a M2M model between an element that is assigned to a
// projector. This element can either be the current one projected, in the
// preview, or in the history, but not more than one once. A projection is
// projector-specific, meaning that once a projection is created for a projector
// and element, these references will not change.
Interface projection {
    id: number;
    options: JSON;

    current_projector_id: projector/current_projection_ids;
    preview_projector_id: projector/preview_projection_ids;
    history_projector_id: projector/history_projection_ids;
    element_id: */projection_ids;
}

Interface projectiondefault {
    id: number;
    name: string;
    display_name: string;

    projector_id: projector/projectiondefault_ids;
    meeting_id: meeting/projectiondefault_ids;
}

Interface projector_message {
    id: number;
    message: HTML;

    projection_ids: (projection/element_id)[];
    current_projector_ids: (projector/current_element_ids)[];
    meeting_id: meeting/projector_message_ids;
}

Interface projector_countdown {
    id: number;
    title: string;
    description: string;
    default_time: number;
    countdown_time: number; // float?
    running: boolean;

    projection_ids: (projection/element_id)[];
    current_projector_ids: (projector/current_element_ids)[];
    meeting_id: meeting/projector_countdown_ids;
}