diff --git a/.github/workflows/models.yml b/.github/workflows/models.yml
new file mode 100644
index 000000000..aed269800
--- /dev/null
+++ b/.github/workflows/models.yml
@@ -0,0 +1,30 @@
+name: Validate models.yml
+on: [push, pull_request]
+jobs:
+  validate:
+    name: Validate models.yml
+    runs-on: ubuntu-latest
+    steps:
+    - name: Set up Go 1.15
+      uses: actions/setup-go@v1
+      with:
+        go-version: 1.15
+
+    - name: Install validator
+      run: go get github.com/OpenSlides/openslides-modelsvalidate/cmd/modelsvalidate
+
+    - name: Check out code
+      uses: actions/checkout@v2
+
+    - name: Validate models.yml
+      run: $HOME/go/bin/modelsvalidate docs/models.yml
+
+  check-old:
+    name: Check old models.txt
+    runs-on: ubuntu-latest
+    steps:
+    - name: Check out code
+      uses: actions/checkout@v2
+
+    - name: Check MD5 hash of old models.txt
+      run: echo "4dee769da047e0169b5fe1280f3ea2f0  docs/models.txt" | md5sum --check
diff --git a/docs/models.yml b/docs/models.yml
new file mode 100644
index 000000000..dcfa6b60c
--- /dev/null
+++ b/docs/models.yml
@@ -0,0 +1,1666 @@
+---
+# Types:
+#     - Nativ datatypes: string, number, boolean, JSON
+#     - HTML: A string with HTML content.
+#     - HTMLVideo: A string with HTML content (with video tags).
+#     - 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.
+#       At the moment we support only X == 6.
+#     - 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.
+#     - <T>[]: This indicates and arbitrary array of the given type. At the moment
+#       we support only some types. You can add JSON Schema properties for items
+#       using the extra property `items`
+# Relations:
+#     - We have the following types: `relation`, `relation-list`, `generic-relation`
+#       and `generic-relation-list`.
+#     - Non-generic relations: The simple syntax for such a field
+#       `to: <collection>/<field>`. This is a reference to a collection. The reverse
+#       relation field in this collection is <field>. E. g. in a motion the field
+#       `category_id` links to one category where the field `motion_ids` contains the
+#       motion id. The simple notation for the field is `motion_category/motion_ids`.
+#       The reverse field has type `relation-list` and is related back to
+#       `motion/category_id`. The type indicates that there are many
+#       motion ids.
+#     - Generic relations: The difference to non-generic relations is that you have a
+#       list of possible collections. Therefor we split the simple notation up to the
+#       properties `collection` and `field`.
+# Structured fields:
+#     - There are template fields (see autoupdate service interface) with a `$` as
+#       the placeholder. We have three different types: `template`,
+#       `structured-relation` and `structured-tag`.
+#     - The type `template` describes a structured field for the given model. The
+#       property `replacement` describes the meaning of the template. The property
+#       `fields` contains the definition for all the fields that come from the template
+#       field.
+#     - The type `structured-relation` describes the content of a related field as a
+#       structured field (with properties `name`, `replacement` and `through`).
+#     - The type `structured-tag` describes the content of a related field as a
+#       structured field where the template is filled with arbitrary strings instead of
+#       instance ids.
+# JSON Schema Properties:
+#     - You can add JSON Schema properties like `enum` and `description` to the fields.
+
+organisation:
+  id: number
+  name: string
+  description: HTML
+
+  # Configs
+  legal_notice: string
+  privacy_policy: string
+  login_text: string
+  theme: string
+  custom_translations: JSON
+
+  committee_ids:
+    type: relation-list
+    to: committee/organisation_id
+  role_ids:
+    type: relation-list
+    to: role/organisation_id
+  superadmin_role_id:
+    type: relation
+    to: role/superadmin_role_for_organisation_id
+  resource_ids:
+    type: relation-list
+    to: resource/organisation_id
+
+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(6)
+
+  role_id:
+    type: relation
+    to: 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:
+    type: relation-list
+    to: meeting/present_user_ids
+  meeting_id:
+    type: relation
+    to: meeting/temporary_user_ids  # Temporary users
+  guest_meeting_ids:
+    type: relation-list
+    to: meeting/guest_ids  # Guests in meetings
+  committee_as_member_ids:
+    type: relation-list
+    to: committee/member_ids
+  committee_as_manager_ids:
+    type: relation-list
+    to: committee/manager_ids
+
+  # Projection
+  projection_ids:
+    type: relation-list
+    to: projection/element_id
+  current_projector_ids:
+    type: relation-list
+    to: 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_$_ids:
+    type: template
+    replacement: meeting_id
+    fields:
+      type: relation-list
+      to: group/user_ids
+  speaker_$_ids:
+    type: template
+    replacement: meeting_id
+    fields:
+      type: relation-list
+      to: speaker/user_id
+  personal_note_$_ids:
+    type: template
+    replacement: meeting_id
+    fields:
+      type: relation-list
+      to: personal_note/user_id
+  supported_motion_$_ids:
+    type: template
+    replacement: meeting_id
+    fields:
+      type: relation-list
+      to: motion/supporter_ids
+  submitted_motion_$_ids:
+    type: template
+    replacement: meeting_id
+    fields:
+      type: relation-list
+      to: motion_submitter/user_id
+  motion_poll_voted_$_ids:
+    type: template
+    replacement: meeting_id
+    fields:
+      type: relation-list
+      to: motion_poll/voted_ids
+  motion_vote_$_ids:
+    type: template
+    replacement: meeting_id
+    fields:
+      type: relation-list
+      to: motion_vote/user_id
+  assignment_candidate_$_ids:
+    type: template
+    replacement: meeting_id
+    fields:
+      type: relation-list
+      to: assignment_candidate/user_id
+  assignment_poll_voted_$_ids:
+    type: template
+    replacement: meeting_id
+    fields:
+      type: relation-list
+      to: assignment_poll/voted_ids
+  assignment_option_$_ids:
+    type: template
+    replacement: meeting_id
+    fields:
+      type: relation-list
+      to: assignment_option/user_id
+  assignment_vote_$_ids:
+    type: template
+    replacement: meeting_id
+    fields:
+      type: relation-list
+      to: assignment_vote/user_id
+
+role:
+  id: number
+  name: string
+  permissions: string[]
+
+  organisation_id:
+    type: relation
+    to: organisation/role_ids
+  superadmin_role_for_organisation_id:
+    type: relation
+    to: organisation/superadmin_role_id
+  user_ids:
+    type: relation-list
+    to: 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.
+resource:
+  id: number
+  token: string
+  filesize: number
+  mimetype: string
+
+  organisation_id:
+    type: relation
+    to: organisation/resource_ids
+
+committee:
+  id: number
+  name:
+    type: string
+    required: true
+  description: HTML
+
+  meeting_ids:
+    type: relation-list
+    to: meeting/committee_id
+  template_meeting_id:
+    type: relation
+    to: meeting/template_for_committee_id
+  default_meeting_id:
+    type: relation
+    to: meeting/default_meeting_for_committee_id
+  member_ids:
+    type: relation-list
+    to: user/committee_as_member_ids
+  manager_ids:
+    type: relation-list
+    to: user/committee_as_manager_ids
+  forward_to_committee_ids:
+    type: relation-list
+    to: committee/receive_forwardings_from_committee_ids
+  receive_forwardings_from_committee_ids:
+    type: relation-list
+    to: committee/forward_to_committee_ids
+  organisation_id:
+    type: relation
+    to: organisation/committee_ids
+    required: true
+
+meeting:
+  id: number
+  welcome_title: string
+  welcome_text: HTMLVideo
+
+  # General
+  name:
+    type: string
+    maxLength: 100
+  description:
+    type: string
+    maxLength: 100
+  location: string
+  start_time: datetime
+  end_time: datetime
+  custom_translations: JSON
+
+  # System
+  url_name:
+    type: string
+    description: For unique urls.
+  template_for_committee_id:
+    type: relation
+    to: committee/template_meeting_id
+  enable_anonymous: boolean
+
+  # Jitsi/Livestream settings
+  conference_show: boolean
+  conference_auto_connect: boolean
+  conference_los_restriction: boolean
+  conference_stream_url: string
+
+  # Projector
+  projector_default_countdown_time: number
+  projector_countdown_warning_time:
+    type: number
+    minimum: 0
+
+  # Exports
+  export_csv_encoding:
+    type: string
+    enum:
+    - utf-8
+    - iso-8859-15
+  export_csv_separator: string
+  export_pdf_pagenumber_alignment:
+    type: string
+    enum:
+    - left
+    - right
+    - center
+  export_pdf_fontsize:
+    type: number
+    enum:
+    - 10
+    - 11
+    - 12
+  export_pdf_pagesize:
+    type: string
+    enum:
+    - A4
+    - A5
+
+  # Agenda
+  agenda_show_subtitles: boolean
+  agenda_enable_numbering: boolean
+  agenda_number_prefix:
+    type: string
+    maxLength: 20
+  agenda_numeral_system:
+    type: string
+    enum:
+    - arabic
+    - roman
+  agenda_item_creation:
+    type: string
+    enum:
+    - always
+    - never
+    - default_yes
+    - default_no
+  agenda_new_items_default_visibility:
+    type: number
+    enum:
+    - 1
+    - 2
+    - 3
+  agenda_show_internal_items_on_projector: boolean
+
+  # List of speakers
+  list_of_speakers_amount_last_on_projector:
+    type: number
+    minimum: 0
+  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:
+    type: relation
+    to: motion_workflow/default_workflow_meeting_id
+    required: true
+  motions_default_amendment_workflow_id:
+    type: relation
+    to: motion_workflow/default_amendment_workflow_meeting_id
+    required: true
+  motions_default_statute_amendment_workflow_id:
+    type: relation
+    to: motion_workflow/default_statute_amendment_workflow_meeting_id
+    required: true
+  motions_preamble: string
+  motions_default_line_numbering:
+    type: string
+    enum:
+    - outside
+    - inline
+    - none
+  motions_line_length:
+    type: number
+    minimium: 40
+  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:
+    type: string
+    enum:
+    - original
+    - changed
+    - diff
+    - agreed
+  motions_default_sorting: string
+  motions_identifier_type:
+    type: string
+    enum:
+    - per_category
+    - serially_numbered
+    - manually
+  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:
+    type: string
+    enum:
+    - freestyle
+    - fulltext
+    - paragraph
+  motions_amendments_multiple_paragraphs: boolean
+  motions_supporters_min_amount:
+    type: number
+    minimum: 0
+  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:
+    type: string
+    enum:
+    - NUMBER_OF_DELEGATES
+    - NUMBER_OF_ALL_PARTICIPANTS
+    - CUSTOM_NUMBER
+  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:
+    type: relation-list
+    to: group/used_as_motion_poll_default_id
+
+  # Users
+  users_sort_by:
+    type: string
+    enum:
+    - first_name
+    - last_name
+    - number
+  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:
+    type: string
+    enum:
+    - ""
+    - WEP
+    - WPA
+    - nopass
+  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_ballot_paper_selection:
+    type: string
+    enum:
+    - NUMBER_OF_DELEGATES
+    - NUMBER_OF_ALL_PARTICIPANTS
+    - CUSTOM_NUMBER
+  assignment_poll_ballot_paper_number: number
+  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:
+    type: relation-list
+    to: group/used_as_assignment_poll_default_id
+
+  projector_ids:
+    type: relation-list
+    to: projector/meeting_id
+  projectiondefault_ids:
+    type: relation-list
+    to: projectiondefault/meeting_id
+  projector_message_ids:
+    type: relation-list
+    to: projector_message/meeting_id
+  projector_countdown_ids:
+    type: relation-list
+    to: projector_countdown/meeting_id
+  tag_ids:
+    type: relation-list
+    to: tag/meeting_id
+  agenda_item_ids:
+    type: relation-list
+    to: agenda_item/meeting_id
+  list_of_speakers_ids:
+    type: relation-list
+    to: list_of_speakers/meeting_id
+  topic_ids:
+    type: relation-list
+    to: topic/meeting_id
+  group_ids:
+    type: relation-list
+    to: group/meeting_id
+  mediafile_ids:
+    type: relation-list
+    to: mediafile/meeting_id
+  motion_ids:
+    type: relation-list
+    to: motion/meeting_id
+  motion_comment_section_ids:
+    type: relation-list
+    to: motion_comment_section/meeting_id
+  motion_category_ids:
+    type: relation-list
+    to: motion_category/meeting_id
+  motion_block_ids:
+    type: relation-list
+    to: motion_block/meeting_id
+  motion_workflow_ids:
+    type: relation-list
+    to: motion_workflow/meeting_id
+  motion_statute_paragraph_ids:
+    type: relation-list
+    to: motion_statute_paragraph/meeting_id
+  motion_poll_ids:
+    type: relation-list
+    to: motion_poll/meeting_id
+  assignment_ids:
+    type: relation-list
+    to: assignment/meeting_id
+  assignment_poll_ids:
+    type: relation-list
+    to: 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_$_id:
+    type: template
+    replacement: location
+    fields:
+      type: relation
+      to:
+        collection: mediafile
+        field:
+          name: used_as_logo_$_in_meeting_id
+          type: structured-tag
+          replacement: location
+  font_$_id:
+    type: template
+    replacement: location
+    fields:
+      type: relation
+      to:
+        collection: mediafile
+        field:
+          name: used_as_font_$_in_meeting_id
+          type: structured-tag
+          replacement: location
+  # Examples:
+  # logo_web_header: Mediafile;
+  # font_italic_pdf: Mediafile;
+  # The client can define these resources. There is no need
+  # to have whitelist/blacklist on the server. The places must
+  # be checked: They must match `[a-z]([a-z_]*[a-z])?` and must
+  # not be longer than 32 characters.
+
+  # Other relations
+  committee_id:
+    type: relation
+    to: committee/meeting_ids
+    required: true
+  default_meeting_for_committee_id:
+    type: relation
+    to: committee/default_meeting_id
+  present_user_ids:
+    type: relation-list
+    to: user/is_present_in_meeting_ids
+  temporary_user_ids:
+    type: relation-list
+    to: user/meeting_id
+  guest_ids:
+    type: relation-list
+    to: user/guest_meeting_ids
+  user_ids:
+    type: number[]
+    decription: Calculated. All ids from temporary_user_ids, guest_ids and all users assigned to groups.
+    read_only: true
+  reference_projector_id:
+    type: relation
+    to: projector/used_as_reference_projector_meeting_id
+
+  default_group_id:
+    type: relation
+    to: group/default_group_for_meeting_id
+    required: true
+  superadmin_group_id:
+    type: relation
+    to: group/superadmin_group_for_meeting_id
+
+group:
+  id: number
+  name:
+    type: string
+    required: true
+  permissions: string[]
+
+  user_ids:
+    type: relation-list
+    to:
+      collection: user
+      field:
+        name: group_$_ids
+        type: structured-relation
+        replacement: meeting_id
+  default_group_for_meeting_id:
+    type: relation
+    to: meeting/default_group_id
+  superadmin_group_for_meeting_id:
+    type: relation
+    to: meeting/superadmin_group_id
+  mediafile_access_group_ids:
+    type: relation-list
+    to: mediafile/access_group_ids
+  mediafile_inherited_access_group_ids:
+    type: relation-list
+    to: mediafile/inherited_access_group_ids
+    description: Calculated field.
+    read_only: true
+  read_comment_section_ids:
+    type: relation-list
+    to: motion_comment_section/read_group_ids
+  write_comment_section_ids:
+    type: relation-list
+    to: motion_comment_section/write_group_ids
+  motion_poll_ids:
+    type: relation-list
+    to: motion_poll/entitled_group_ids
+  assignment_poll_ids:
+    type: relation-list
+    to: assignment_poll/entitled_group_ids
+  used_as_motion_poll_default_id:
+    type: relation
+    to: meeting/motion_poll_default_group_ids
+  used_as_assignment_poll_default_id:
+    type: relation
+    to: meeting/assignment_poll_default_group_ids
+  meeting_id:
+    type: relation
+    to: meeting/group_ids
+    required: true
+
+personal_note:
+  id: number
+  note: HTML
+  star: boolean
+
+  user_id:
+    type: relation
+    to:
+      collection: user
+      field:
+        name: personal_note_$_ids
+        type: structured-relation
+        replacement: meeting_id
+  content_object_id:
+    type: generic-relation
+    to:
+      collection:
+        - motion
+      field: personal_note_ids
+
+tag:
+  id: number
+  name:
+    type: string
+    required: true
+
+  tagged_ids:
+    type: generic-relation-list
+    to:
+      collection:
+        - agenda_item
+        - assignment
+        - motion
+        - topic
+      field: tag_ids
+  meeting_id:
+    type: relation
+    to: meeting/tag_ids
+    required: true
+
+agenda_item:
+  id: number
+  item_number: string
+  comment: string
+  closed: boolean
+  type:
+    type: number
+    enum:
+    - 1
+    - 2
+    - 3
+  duration:
+    type: number
+    description: Given in seconds
+    minimum: 0
+  is_internal:
+    type: boolean
+    description: Calculated by the server
+    read_only: true
+  is_hidden:
+    type: boolean
+    description: Calculated by the server
+    read_only: true
+  level:
+    type: number
+    description: Calculated by the server
+    read_only: true
+  weight:
+    type: number
+    default: 0
+
+  content_object_id:
+    type: generic-relation
+    to:
+      collection:
+        - motion
+        - motion_block
+        - assignment
+        - topic
+      field: agenda_item_id
+    required: true
+  parent_id:
+    type: relation
+    to: agenda_item/child_ids
+  child_ids:
+    type: relation-list
+    to: agenda_item/parent_id
+  tag_ids:
+    type: relation-list
+    to: tag/tagged_ids
+  projection_ids:
+    type: relation-list
+    to: projection/element_id
+  current_projector_ids:
+    type: relation-list
+    to: projector/current_element_ids
+  meeting_id:
+    type: relation
+    to: meeting/agenda_item_ids
+    required: true
+
+list_of_speakers:
+  id: number
+  closed: boolean
+
+  content_object_id:
+    type: generic-relation
+    to:
+      collection:
+        - motion
+        - motion_block
+        - assignment
+        - topic
+        - mediafile
+      field: list_of_speakers_id
+    required: true
+  speaker_ids:
+    type: relation-list
+    to: speaker/list_of_speakers_id
+  projection_ids:
+    type: relation-list
+    to: projection/element_id
+  current_projector_ids:
+    type: relation-list
+    to: projector/current_element_ids
+  meeting_id:
+    type: relation
+    to: meeting/list_of_speakers_ids
+    required: true
+
+speaker:
+  id: number
+  begin_time:
+    type: datetime
+    read_only: true
+  end_time:
+    type: datetime
+    read_only: true
+  weight:
+    type: number
+    default: 0
+  marked: boolean
+
+  list_of_speakers_id:
+    type: relation
+    to: list_of_speakers/speaker_ids
+    required: true
+  user_id:
+    type: relation
+    to:
+      collection: user
+      field:
+        name: speaker_$_ids
+        type: structured-relation
+        replacement: meeting_id
+    required: true
+
+topic:
+  id: number
+  title:
+    type: string
+    required: true
+  text: HTMLVideo
+
+  attachment_ids:
+    type: relation-list
+    to: mediafile/attachment_ids
+  agenda_item_id:
+    type: relation
+    to: agenda_item/content_object_id
+    required: true
+  list_of_speakers_id:
+    type: relation
+    to: list_of_speakers/content_object_id
+    required: true
+  tag_ids:
+    type: relation-list
+    to: tag/tagged_ids
+  meeting_id:
+    type: relation
+    to: meeting/topic_ids
+    required: true
+
+motion:
+  id: number
+  number: string
+  sequential_number:
+    type: number
+    description: The (positive) serial number of this motion. This number is auto-generated and read-only.
+    read_only: true
+  title:
+    type: string
+    required: true
+  text: HTML
+  amendment_paragraph_$:
+    type: template
+    replacement: paragraph_number
+    fields: HTML
+  modified_final_version: HTML
+  reason: HTML
+  category_weight:
+    type: number
+    default: 0
+  state_extension: string
+  recommendation_extension: string
+  sort_weight:
+    type: number
+    default: 0
+  created:
+    type: datetime
+    read_only: true
+  last_modified:
+    type: datetime
+    read_only: true
+
+  lead_motion_id:
+    type: relation
+    to: motion/amendment_ids
+  amendment_ids:
+    type: relation-list
+    to: motion/lead_motion_id
+  sort_parent_id:
+    type: relation
+    to: motion/sort_child_ids
+  sort_child_ids:
+    type: relation-list
+    to: motion/sort_parent_id
+  origin_id:
+    type: relation
+    to: motion/derived_motion_ids  # Note: The related motions may not be in the same meeting
+  derived_motion_ids:
+    type: relation-list
+    to: motion/origin_id  # Note: The related motions may not be in the same meeting
+  forwarding_tree_motion_ids: number[]  # Calculated: All children (derived_motion_ids), grand children, ... and all parents (origin_id).
+  state_id:
+    type: relation
+    to: motion_state/motion_ids
+    required: true
+  recommendation_id:
+    type: relation
+    to: motion_state/motion_recommendation_ids
+  recommendation_extension_reference_ids:
+    type: generic-relation-list
+    to:
+      collection:
+        - motion
+      field: referenced_in_motion_recommendation_extension_ids
+  referenced_in_motion_recommendation_extension_ids:
+    type: relation-list
+    to: motion/recommendation_extension_reference_ids
+  category_id:
+    type: relation
+    to: motion_category/motion_ids
+  block_id:
+    type: relation
+    to: motion_block/motion_ids
+  submitter_ids:
+    type: relation-list
+    to: motion_submitter/motion_id
+  supporter_ids:
+    type: relation-list
+    to:
+      collection: user
+      field:
+        name: supported_motion_$_ids
+        type: structured-relation
+        replacement: meeting_id
+  poll_ids:
+    type: relation-list
+    to: motion_poll/motion_id
+  change_recommendation_ids:
+    type: relation-list
+    to: motion_change_recommendation/motion_id
+  statute_paragraph_id:
+    type: relation
+    to: motion_statute_paragraph/motion_ids
+  comment_ids:
+    type: relation-list
+    to: motion_comment/motion_id
+  agenda_item_id:
+    type: relation
+    to: agenda_item/content_object_id
+  list_of_speakers_id:
+    type: relation
+    to: list_of_speakers/content_object_id
+    required: true
+  tag_ids:
+    type: relation-list
+    to: tag/tagged_ids
+  attachment_ids:
+    type: relation-list
+    to: mediafile/attachment_ids
+  projection_ids:
+    type: relation-list
+    to: projection/element_id
+  current_projector_ids:
+    type: relation-list
+    to: projector/current_element_ids
+  personal_note_ids:
+    type: relation-list
+    to: personal_note/content_object_id
+  meeting_id:
+    type: relation
+    to: meeting/motion_ids
+    required: true
+
+motion_submitter:
+  id: number
+  weight:
+    type: number
+    default: 0
+
+  user_id:
+    type: relation
+    to:
+      collection: user
+      field:
+        name: submitted_motion_$_ids
+        type: structured-relation
+        replacement: meeting_id
+  motion_id:
+    type: relation
+    to: motion/submitter_ids
+
+motion_comment:
+  id: number
+  comment: HTML
+
+  motion_id:
+    type: relation
+    to: motion/comment_ids
+    required: true
+  section_id:
+    type: relation
+    to: motion_comment_section/comment_ids
+    required: true
+
+motion_comment_section:
+  id: number
+  name:
+    type: string
+    required: true
+  weight:
+    type: number
+    default: 0
+
+  comment_ids:
+    type: relation-list
+    to: motion_comment/section_id
+  read_group_ids:
+    type: relation-list
+    to: group/read_comment_section_ids
+  write_group_ids:
+    type: relation-list
+    to: group/write_comment_section_ids
+  meeting_id:
+    type: relation
+    to: meeting/motion_comment_section_ids
+    required: true
+
+motion_category:
+  id: number
+  name:
+    type: string
+    required: true
+  prefix:
+    type: string
+    required: true
+  weight:
+    type: number
+    default: 0
+  level:
+    type: number
+    description: Calculated field.
+    read_only: true
+
+  parent_id:
+    type: relation
+    to: motion_category/child_ids
+  child_ids:
+    type: relation-list
+    to: motion_category/parent_id
+  motion_ids:
+    type: relation-list
+    to: motion/category_id
+  meeting_id:
+    type: relation
+    to: meeting/motion_category_ids
+    required: true
+
+motion_block:
+  id: number
+  title:
+    type: string
+    required: true
+  internal: boolean
+
+  motion_ids:
+    type: relation-list
+    to: motion/block_id
+  agenda_item_id:
+    type: relation
+    to: agenda_item/content_object_id
+  list_of_speakers_id:
+    type: relation
+    to: list_of_speakers/content_object_id
+    required: true
+  projection_ids:
+    type: relation-list
+    to: projection/element_id
+  current_projector_ids:
+    type: relation-list
+    to: projector/current_element_ids
+  meeting_id:
+    type: relation
+    to: meeting/motion_block_ids
+    required: true
+
+motion_change_recommendation:
+  id: number
+  rejected: boolean
+  internal: boolean
+  type:
+    type: number
+    enum:
+    - 0
+    - 1
+    - 2
+    - 3
+  other_description: string
+  line_from:
+    type: number
+    minimum: 0
+  line_to:
+    type: number
+    minimum: 0
+  text: HTML
+  creation_time:
+    type: datetime
+    read_only: true
+
+  motion_id:
+    type: relation
+    to: motion/change_recommendation_ids
+    required: true
+
+motion_state:
+  id: number
+  name:
+    type: string
+    required: true
+  recommendation_label: string
+  css_class:
+    type: string
+    enum:
+    - gray
+    - red
+    - green
+    - lightblue
+    - yellow
+  restrictions:
+    type: string[]
+    items:
+      enum:
+      - motions.can_see_internal
+      - motions.can_manage_metadata
+      - motions.can_manage
+      - is_submitter
+  allow_support: boolean
+  allow_create_poll: boolean
+  allow_submitter_edit: boolean
+  set_number: boolean
+  show_state_extension_field: boolean
+  merge_amendment_into_final:
+    type: number
+    default: 0
+    enum:
+    - -1
+    - 0
+    - 1
+  show_recommendation_extension_field: boolean
+
+  next_state_ids:
+    type: relation-list
+    to: motion_state/previous_state_ids
+  previous_state_ids:
+    type: relation-list
+    to: motion_state/next_state_ids
+  motion_ids:
+    type: relation-list
+    to: motion/state_id
+  motion_recommendation_ids:
+    type: relation-list
+    to: motion/recommendation_id
+  workflow_id:
+    type: relation
+    to: motion_workflow/state_ids
+    required: true
+  first_state_of_workflow_id:
+    type: relation
+    to: motion_workflow/first_state_id
+
+motion_workflow:
+  id: number
+  name:
+    type: string
+    required: true
+
+  state_ids:
+    type: relation-list
+    to: motion_state/workflow_id
+  first_state_id:
+    type: relation
+    to: motion_state/first_state_of_workflow_id
+    required: true
+  default_workflow_meeting_id:
+    type: relation
+    to: meeting/motions_default_workflow_id
+  default_amendment_workflow_meeting_id:
+    type: relation
+    to: meeting/motions_default_amendment_workflow_id
+  default_statute_amendment_workflow_meeting_id:
+    type: relation
+    to: meeting/motions_default_statute_amendment_workflow_id
+  meeting_id:
+    type: relation
+    to: meeting/motion_workflow_ids
+    required: true
+
+motion_statute_paragraph:
+  id: number
+  title:
+    type: string
+    required: true
+  text: HTML
+  weight:
+    type: number
+    default: 0
+
+  motion_ids:
+    type: relation-list
+    to: motion/statute_paragraph_id
+  meeting_id:
+    type: relation
+    to: meeting/motion_statute_paragraph_ids
+    required: true
+
+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:
+    type: relation
+    to: motion/poll_ids
+  option_ids:
+    type: relation-list
+    to: motion_option/poll_id
+  voted_ids:
+    type: relation-list
+    to:
+      collection: user
+      field:
+        name: motion_poll_voted_$_ids
+        type: structured-relation
+        replacement: meeting_id
+  entitled_group_ids:
+    type: relation-list
+    to: group/motion_poll_ids
+  projection_ids:
+    type: relation-list
+    to: projection/element_id
+  current_projector_ids:
+    type: relation-list
+    to: projector/current_element_ids
+  meeting_id:
+    type: relation
+    to: meeting/motion_poll_ids
+
+motion_option:
+  id: number
+  yes: decimal(6)
+  no: decimal(6)
+  abstain: decimal(6)
+
+  poll_id:
+    type: relation
+    to: motion_poll/option_ids
+  vote_ids:
+    type: relation-list
+    to: motion_vote/option_id
+
+motion_vote:
+  id: number
+  weight: decimal(6)
+  value: string
+
+  option_id:
+    type: relation
+    to: motion_option/vote_ids
+  user_id:
+    type: relation
+    to:
+      collection: user
+      field:
+        name: motion_vote_$_ids
+        type: structured-relation
+        replacement: meeting_id
+
+assignment:
+  id: number
+  title:
+    type: string
+    required: true
+  description: HTML
+  open_posts:
+    type: number
+    minimum: 0
+  phase:
+    type: number
+    enum:
+    - 1
+    - 2
+    - 3
+  default_poll_description: string
+  number_poll_candidates: boolean
+
+  candidate_ids:
+    type: relation-list
+    to: assignment_candidate/assignment_id
+  poll_ids:
+    type: relation-list
+    to: assignment_poll/assignment_id
+  agenda_item_id:
+    type: relation
+    to: agenda_item/content_object_id
+  list_of_speakers_id:
+    type: relation
+    to: list_of_speakers/content_object_id
+    required: true
+  tag_ids:
+    type: relation-list
+    to: tag/tagged_ids
+  attachment_ids:
+    type: relation-list
+    to: mediafile/attachment_ids
+  projection_ids:
+    type: relation-list
+    to: projection/element_id
+  current_projector_ids:
+    type: relation-list
+    to: projector/current_element_ids
+  meeting_id:
+    type: relation
+    to: meeting/assignment_ids
+    required: true
+
+assignment_candidate:
+  id: number
+  weight:
+    type: number
+    default: 0
+
+  assignment_id:
+    type: relation
+    to: assignment/candidate_ids
+  user_id:
+    type: relation
+    to:
+      collection: user
+      field:
+        name: assignment_candidate_$_ids
+        type: structured-relation
+        replacement: meeting_id
+
+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:
+    type: relation
+    to: assignment/poll_ids
+  voted_ids:
+    type: relation-list
+    to:
+      collection: user
+      field:
+        name: assignment_poll_voted_$_ids
+        type: structured-relation
+        replacement: meeting_id
+  entitled_group_ids:
+    type: relation-list
+    to: group/assignment_poll_ids
+  option_ids:
+    type: relation-list
+    to: assignment_option/poll_id
+  projection_ids:
+    type: relation-list
+    to: projection/element_id
+  current_projector_ids:
+    type: relation-list
+    to: projector/current_element_ids
+  meeting_id:
+    type: relation
+    to: meeting/assignment_poll_ids
+
+assignment_option:
+  id: number
+  yes: decimal(6)
+  no: decimal(6)
+  abstain: decimal(6)
+  weight:
+    type: number
+    default: 0
+
+  poll_id:
+    type: relation
+    to: assignment_poll/option_ids
+  user_id:
+    type: relation
+    to:
+      collection: user
+      field:
+        name: assignment_option_$_ids
+        type: structured-relation
+        replacement: meeting_id
+  vote_ids:
+    type: relation-list
+    to: assignment_vote/option_id
+
+assignment_vote:
+  id: number
+  value: string
+  weight: decimal(6)
+
+  option_id:
+    type: relation
+    to: assignment_option/vote_ids
+  user_id:
+    type: relation
+    to:
+      collection: user
+      field:
+        name: assignment_vote_$_ids
+        type: structured-relation
+        replacement: meeting_id
+
+# Mediafiles are delivered by the mediafile server with the URL
+# `<media-prefix>/media/<meeting_id>/path`
+mediafile:
+  id: number
+  title:
+    type: string
+    description: Title and parent_id must be unique.
+  is_directory: boolean
+  filesize:
+    type: number
+    description: In bytes, not the human readable format anymore.
+    read_only: true
+  filename:
+    type: string
+    descriptin: The uploaded filename. Will be used for downloading. Only writeable on create.
+    required: true
+  mimetype: string
+  pdf_information: JSON
+  create_timestamp: datetime
+  has_inherited_access_groups:
+    type: boolean
+    description: Calculated field.
+    read_only: true
+
+  inherited_access_group_ids:
+    type: relation-list
+    to: group/mediafile_inherited_access_group_ids
+    description: Calculated field.
+    read_only: true
+  access_group_ids:
+    type: relation-list
+    to: group/mediafile_access_group_ids
+  parent_id:
+    type: relation
+    to: mediafile/child_ids
+  child_ids:
+    type: relation-list
+    to: mediafile/parent_id
+  list_of_speakers_id:
+    type: relation
+    to: list_of_speakers/content_object_id
+    required: true
+  projection_ids:
+    type: relation-list
+    to: projection/element_id
+  current_projector_ids:
+    type: relation-list
+    to: projector/current_element_ids
+  attachment_ids:
+    type: generic-relation-list
+    to:
+      collection:
+        - motion
+        - topic
+        - assignment
+      field: attachment_ids
+  meeting_id:
+    type: relation
+    to: meeting/mediafile_ids
+    required: true
+
+  # Reverse relations for meetings, if a mediafile is used as a special resource
+  used_as_logo_$_in_meeting_id:
+    type: template
+    replacement: location
+    fields:
+      type: relation
+      to:
+        collection: meeting
+        field:
+          name: logo_$_id
+          type: structured-tag
+          replacement: location
+  used_as_font_$_in_meeting_id:
+    type: template
+    replacement: location
+    fields:
+      type: relation
+      to:
+        collection: meeting
+        field:
+          name: font_$_id
+          type: structured-tag
+          replacement: location
+
+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:
+    type: relation-list
+    to: projection/current_projector_id
+  # A relation to the currently projected elements to get a direct link, if
+  # the element is projected.
+  current_element_ids:
+    type: generic-relation-list
+    to:
+      collection:
+        - motion
+        - mediafile
+        - list_of_speakers
+        - motion_block
+        - assignment
+        - agenda_item
+        - user
+        - assignment_poll
+        - motion_poll
+        - projector_message
+        - projector_countdown
+      field: current_projector_ids
+  preview_projection_ids:
+    type: relation-list
+    to: projection/preview_projector_id
+  history_projection_ids:
+    type: relation-list
+    to: projection/history_projector_id
+  used_as_reference_projector_meeting_id:
+    type: relation
+    to: meeting/reference_projector_id
+  projectiondefault_ids:
+    type: relation-list
+    to: projectiondefault/projector_id
+  meeting_id:
+    type: relation
+    to: 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.
+projection:
+  id: number
+  options: JSON
+
+  current_projector_id:
+    type: relation
+    to: projector/current_projection_ids
+  preview_projector_id:
+    type: relation
+    to: projector/preview_projection_ids
+  history_projector_id:
+    type: relation
+    to: projector/history_projection_ids
+  element_id:
+    type: generic-relation
+    to:
+      collection:
+        - motion
+        - mediafile
+        - list_of_speakers
+        - motion_block
+        - assignment
+        - agenda_item
+        - user
+        - assignment_poll
+        - motion_poll
+        - projector_message
+        - projector_countdown
+      field: projection_ids
+
+projectiondefault:
+  id: number
+  name: string
+  display_name: string
+
+  projector_id:
+    type: relation
+    to: projector/projectiondefault_ids
+  meeting_id:
+    type: relation
+    to: meeting/projectiondefault_ids
+
+projector_message:
+  id: number
+  message: HTML
+
+  projection_ids:
+    type: relation-list
+    to: projection/element_id
+  current_projector_ids:
+    type: relation-list
+    to: projector/current_element_ids
+  meeting_id:
+    type: relation
+    to: meeting/projector_message_ids
+
+projector_countdown:
+  id: number
+  title: string
+  description: string
+  default_time: number
+  countdown_time: number  # float?
+  running: boolean
+
+  projection_ids:
+    type: relation-list
+    to: projection/element_id
+  current_projector_ids:
+    type: relation-list
+    to: projector/current_element_ids
+  meeting_id:
+    type: relation
+    to: meeting/projector_countdown_ids