> ## Documentation Index
> Fetch the complete documentation index at: https://help.qrtub.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom Field Types

> The six types a custom field can be, what each one gates, and how to choose between a fixed list of values (Allowed Values) and a live pointer to another record (Reference).

A custom field is one of six types, chosen when you create it and changeable afterward. The
type decides what the input looks like on the Item form, how the value is stored, and which
of the field's other options you are allowed to switch on.

## The six types

| Type       | Stored as                 | On the Item form                                                       | Use it for                                  |
| ---------- | ------------------------- | ---------------------------------------------------------------------- | ------------------------------------------- |
| **Text**   | A string                  | A text box, or a picker if you give it allowed values                  | Serial numbers, locations, statuses, URLs   |
| **Number** | A number                  | A number box                                                           | Quantities, hours, meter readings           |
| **Date**   | A date only, `YYYY-MM-DD` | A date picker                                                          | Installation date, warranty end             |
| **Yes/No** | `true` or `false`         | A checkbox                                                             | Flags — insured, decommissioned             |
| **List**   | An array of strings       | A multi-select picker, or a comma-separated box with no allowed values | Anything an Item can have several of        |
| **UUID**   | The ID of another record  | A dropdown of records to point at                                      | A responsible person, a parent Item, a site |

A Date field holds no time of day. It is stored as `YYYY-MM-DD`, displayed in the format of
whoever is looking at it, and a CSV import must use `YYYY-MM-DD` — other formats are
rejected row by row.

## What each type gates

Some options only appear for some types, which is the most common reason an option looks
greyed out:

* **Allowed Values** — Text and List only. On any other type the editor says so and hides
  the list. See [Allowed Values](/fields/allowed-values).
* **Multiple Values** and **Allow New Values** — List only. Both checkboxes stay disabled
  until you switch the Field Type to List; the tooltip on each says the same thing. See
  [Allow New Values](/fields/allow-new-values).
* **Reference configuration** — offered on a new field only when the type is UUID. See
  [Reference Fields](/fields/reference-fields).

Multiple Values is what separates a single-select from a multi-select. With it off, a List
field still uses a picker but keeps only the last value you choose; with it on, the field
holds as many values as you select.

## Which type do I need?

Start with what the value *is*:

* **A quantity or reading** → Number, not Text. A Number field rejects anything that is not
  a number on CSV import; a Text field accepts whatever gets typed, typos included.
* **A date** → Date, not Text, so it gets a date picker and a consistent stored format.
* **One of a short, known set of options** → Text with allowed values (one value per Item),
  or List with allowed values and Multiple Values on (several per Item).
* **Free text nobody will filter on** → Text with no allowed values.
* **Another record already in QRtub** → UUID with a reference type. Anything else means
  retyping a name that will eventually go stale.

## Allowed Values or a Reference field?

These are the two options people mix up, and the difference is where the value lives.

**Allowed Values** is a fixed list of literal values you author on the field itself —
`operational`, `in_repair`, `retired`. The Item stores one of those strings. You maintain the
list by hand in the Collection's field settings.

**A Reference field** holds no value of its own. It stores the ID of another record — a team
member, another Item, or a Collection — and displays that record's current name and image.
Change the referenced record's name and every Item pointing at it shows the new name, because
nothing was ever copied. No allowed-values list applies to a reference field; the options in
its dropdown are whatever records exist.

So: a short vocabulary you invented is Allowed Values. A pointer at something that already
exists elsewhere in QRtub is a Reference field.

## A note on UUID without a reference

Choosing UUID and leaving the reference type unset gives you a plain text box, not a
dropdown — the field has nothing to point at. Set the reference type as well, or pick Text
instead.

## Related

* [Allowed Values](/fields/allowed-values)
* [Reference Fields](/fields/reference-fields)
* [Creating a Custom Field](/fields/creating-a-field)
* [Core Fields vs. Custom Fields](/fields/core-vs-custom)