# Simple data types

The following are general requirements for the content and formatting of simple
data types in the XML spec.

> [!NOTE]
> **Note:** Omit all optional data that doesn't have a value from your XML feeds.

## xs:string

Keep the following best practices in mind when you use the `xs:string` data
type:

- Always trim the string to remove leading and trailing white space.
- If the string is presented to end users, such as with party names, office titles, or proper names, convert the data to Title Case when possible to aid readability.

## Dates and times

> [!NOTE]
> **Note:** [ISO-8601](https://en.wikipedia.org/wiki/ISO_8601) requires dates to use the [Gregorian
> calendar](https://en.wikipedia.org/wiki/Gregorian_calendar#Description). Dates in feeds should be converted to the Gregorian calendar if they originate from sources using other calendars.

> [!IMPORTANT]
> **Important:** Make sure to provide the exact date as soon as it's available.

### xs:date

When you use the `xs:date` data type, enter it in
[ISO-8601](https://en.wikipedia.org/wiki/ISO_8601) format.

### xs:dateTime

When you use the `xs:dateTime` data type, enter it in
[ISO-8601](https://en.wikipedia.org/wiki/ISO_8601) format.

### PartialDate

`PartialDate` is a union that lets you set dates in
[ISO-8601](https://en.wikipedia.org/wiki/ISO_8601) format at different levels of
specificity:

- Specific date as `YYYY-MM-DD`
- Period of one month as `YYYY-MM`
- Period of one year as `YYYY`

Partial dates are interpreted as the latest possible date in the range (unless
otherwise noted). E.g. When a `PartialDate` of `2026-01` is supplied, this is
interpreted as `2026-01-31`. If an event were to drift into `2026-02`, it would
be important to update the `PartialDate` value on-or-before `2026-01-31` to
avoid validation errors.

## xs:boolean

When you use the `xs:boolean` data type, enter it with a value of either `true`
or `false` (case-sensitive).

## xs:language

When you use the `xs:language` data type, enter it as a two-character,
lower-case value that corresponds to the [ISO
639](https://en.wikipedia.org/wiki/ISO_639) standard.