# Relations
## Relation field
The relationship field is a concept specific to Daxium-Air. It allows the user to select another form (then called sub-form) and link it to the one they are filling out. Once your relationship field is added to the form, choose the forms that will be linked from the **Forms** drop-down list.
Relationship field options:
* **Selection**: attach an existing child submissions ([broadcasted](/user-documentation/build/building-forms/submission-broadcast.md), [assigned](/user-documentation/build/building-forms/workflow-and-assignation.md), searched, created on mobile)
* Manual: choose from a list of submissions
* Camera: Allows you to scan barcodes with your camera to select a child submission (Mobile only)
* External scan: Allows you to scan barcodes with an external scanner to select a child submission (Mobile only)
* NFC: See the section below (Android only)
* **Creation**: Create a sub-submission of the form
* Send child submission upon creation: If unticked, the child submissions will only be sent to the back office when you send the main submission. If ticked, the child submissions are sent as soon as they are created (Mobile only)
* **Edition for child submissions:** Allows to edit an existing linked or created child submission
* **Allow multiple child submissions**: add several child submissions to the main submission
* **Countable relation: allow a count for each child submission**: Allows you to link a quantity for each of your child submission
* **Plan view**: add a PDF or image file to edit it and attach child submissions to it
* **Visualisation:** Allows you to choose different options to visualise the submissions in the relation field. You can configure distinct options for the web & mobile platforms to match your needs
***
## NFC — Selecting a relation via NFC
{% hint style="info" %}
Daxium-Air's NFC relation selection allows you to **associate an NFC tag with a related submission** (use cases: personnel, materials, equipment, etc.) in order to **instantly select** it in another form. This method replaces or complements manual search and QR codes, offering a faster, more reliable, and more secure approach.
{% endhint %}
{% hint style="warning" %}
NFC selection in relations is currently **Android only**.
{% endhint %}
Setting up NFC selection requires four steps:
1. **Enable NFC tag search on the subform** — allow the child form to be looked up by NFC.
2. **Enable NFC selection on the relation field** — activate the NFC option in the parent form's relation field.
3. **Write a submission to an NFC tag** — link a specific submission to a physical tag via the Admin NFC menu.
4. **Use the tag in the field** — scan the tag while filling in a submission to instantly select the linked record.
### Step 1 — Enable NFC search on the subform
Go to the **relevant** form (the one that will be called by another, e.g., *Internal Signatory Form*).
1. Open the form configuration.
2. Check **"Allow NFC tag search from a parent relationship"**. Customize the **NFC tag naming**: select the fields used to clearly identify the submission (e.g., *Status*, *First Name*, *Last Name*).
{% hint style="success" %}
Choose unique and easily readable fields (e.g., "Technician – First Name Last Name").
{% endhint %}
### Step 2 — Enable NFC selection in the parent form
From the **parent** form (the one that calls the relationship, e.g., *Work Order* or *Service Request*):
1. Access the **Relation** type field.
2. In the **field options**, check **"NFC"** in the *Selection* section.
{% hint style="info" %}
This option allows you to **select a submission** via an NFC tag, without manual searching.
{% endhint %}
### Step 3 — Write a submission to an NFC tag
Once the forms are configured, you can **associate your submissions with NFC tags**.
1. In the Daxium-Air application, open the **Admin NFC** menu. If the menu is not present, add it from the [customization tool](/user-documentation/build/building-apps/app-configuration.md): Action = *NFC Configuration*.
2. The writable submissions appear in the list. Select the desired submission.
3. Tap **Write on tag** then bring a compatible NFC tag close to the smartphone.
4. The confirmation message appears: the tag is now linked to the submission.
{% hint style="success" %}
You can filter submissions not yet written to a tag, and view the number of linked submissions per entry.
{% endhint %}
### Step 4 — Using the NFC tag in the field
When entering a **parent** submission, the relationship field (e.g., *Authorized Person* or *Equipment concerned*) can now be filled in **by simple NFC scan**.
1. Touch the relationship field.
2. The NFC reading screen appears.
3. Bring the phone close to the NFC badge/tag: the linked submission is automatically selected and displayed.
{% hint style="info" %}
Scanning the tag instantly triggers the selection of the correct submission, without error and without manual input.
{% endhint %}
### Good to know
* Standard NFC tags (type NTAG213/215/216) are compatible.
* The tag does not contain **any sensitive data**, only a reference identifier.
* Access rights to the submission remain managed by Daxium-Air permissions.
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