Version 2022.1.0


This specification is a sub-specification of the ODK XForms Specification. It describes a semantic layer that identifies the subject of a form (“entity”) and its properties. Consumers that implement this specification can process form submissions to extract entity information based on the directives provided in the form definition.


Entity: A uniquely-identified thing that a form is about.

Dataset: A set of Entities of the same type.

Entity Property: A named value that belongs to an Entity.

Immutable System Property: An Entity Property that is used by the system and that can’t be changed (dataset, id)

Mutable System Property: An Entity Property that is used by the system and that can be changed (label)

User-defined Property: Properties with arbitrary names defined by the form designer

Entity Actions: Actions that can be taken on Entities (create)

Example of an entity-creating form

<?xml version="1.0"?>
<h:html xmlns="http://www.w3.org/2002/xforms" xmlns:entities="http://www.opendatakit.org/xforms/entities" xmlns:ev="http://www.w3.org/2001/xml-events" xmlns:h="http://www.w3.org/1999/xhtml" xmlns:jr="http://openrosa.org/javarosa" xmlns:odk="http://www.opendatakit.org/xforms" xmlns:orx="http://openrosa.org/xforms" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <h:title>Trees registration</h:title>
    <model odk:xforms-version="1.0.0" entities:entities-version="2022.1.0">
        <data id="trees_registration" version="2022110901">
            <entity dataset="trees" id="" create="">
      <bind nodeset="/data/location" type="geopoint" entities:saveto="geometry" />
      <bind nodeset="/data/species" type="string" entities:saveto="species" />

      <bind jr:preload="uid" nodeset="/data/meta/instanceID" readonly="true()" type="string"/>

      <bind nodeset="/data/meta/entity/@id" type="string"/>
      <setvalue event="odk-instance-first-load" ref="/data/meta/entity/@id" value="uuid()"/>
      <bind nodeset="/data/meta/entity/@create" type="string" calculate="true()"/>
      <bind nodeset="/data/meta/entity/label" calculate="/data/species"  type="string"/>


This specification uses the http://www.opendatakit.org/xforms/entities namespace for attributes added to nodes defined by the ODK XForms spec. In this document, the corresponding prefix used is entities.

Additions to the main instance are NOT namespaced. The specification describes exact XPath paths that consumers must look for.


Consumers of the ODK XForms specification may opt into this entities specification but don’t have to. For this reason, the entities layer is versioned separately from ODK XForms using the entities-version attribute in the http://www.opendatakit.org/xforms/entities namespace.

The specification is versioned using a YYYY.NN.MM scheme:

  • YYYY: the year of the release
  • NN: the count of the release within the year.
  • MM: the patch version. This is incremented when changes that don’t impact compatibility are made to the specification document.

The YYYY.NN components of the version are only changed when a consumer built for an earlier version can no longer correctly use a form definition. For example, a version update will likely be made when multiple entities per form are supported.

Consumers MUST reject forms with a version code that is newer than what they can process.

Declaring that a form creates entities

Entities are declared in an entity element in the meta block of the form definition. The entity element:

  • MUST be a direct child of meta in the primary instance.
  • MUST have attribute id populated by a RFC 4122 version 4 UUID
    • Consumers of submissions that create entities MUST fail to create entities that don’t have a UUID id
  • MUST have attribute dataset representing the target Dataset for entities created from submissions of this form
    • Dataset names follow the same rules as form field names (valid XML identifiers) and additionally MUST NOT include . or start with __
  • MUST have a create attribute populated with a “1” or “true” if the entity should be created
    • Consumers of submissions that create entities MUST interpret “1” or “true” as indications to create an entity and any other value as indication not to create an entity
  • MUST have a direct child label representing a human-readable label

Identifying entity properties

The entities:saveto bind attribute declares that the form field specified by the nodeset attribute on the bind should be saved as an Entity Property. The attribute’s value is the Entity Property’s name and and has the following restrictions:

  • name and label are reserved property names (for use when datasets are represented as itemset CSVs)
  • Property names with __ prefixes are reserved
  • Property names follow the same rules as form field names (valid XML identifiers)

The set of all Entity Properties defined across all forms that populate a specific Dataset define that Dataset’s schema.