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

# The expansion object

> A set of cards released together.

An expansion is a set released together: Base Set, 151, Evolving Skies. It belongs to exactly one
[series](/series/object), and every [card](/cards/object) belongs to exactly one expansion. Ids
are short and stable: `base1`, `sv03.5`, `swsh7`.

## Counting cards

Two counts, and they disagree on purpose:

<ResponseField name="card_count_official" type="number | null">
  The printed set size, the number on the bottom of the card. Excludes secret rares.
</ResponseField>

<ResponseField name="card_count_total" type="number | null">
  Everything the expansion actually contains, secret rares included.
</ResponseField>

A card numbered 199/165 is not a mistake: 165 is official, 199 is inside total. 151, the set
below, contains exactly that card. `sv03.5-199`, a Special illustration rare Charizard ex, sits
inside a 207-card total against a 165-card official count.

## Legality

`legal_standard` and `legal_expanded` say whether the expansion is tournament-legal in each
format. `null` means unknown, not banned: no legality data is available for that expansion.

## Palette

`palette` is up to four dominant colours from the expansion's own logo, most prominent first, as
`#rrggbb`. Build a gradient or an accent from the set's real artwork instead of picking one by
hand for every set you ship.

They are the colours the logo contains, in the proportion it contains them. Base Set returns
`["#fac32c", "#2a2e54", "#6d2239", "#3c5da4"]`: its gold, its navy, the maroon of the Charizard,
the blue behind it. A logo built on a heavy black outline leads with a near-black, because that
genuinely is its most prominent colour. If you want an accent rather than a backdrop, pick the
most saturated entry rather than the first.

Fewer than four is a real answer, not a truncated one. A two-tone logo has two, and the list is
never padded with colours the image does not contain. `null` means there is nothing to give: no
logo is available, or its pixels are all transparent. Render your own fallback.

Series carry the same field, taken from the series logo, so a screen showing a series and its
expansions can theme both.

## Example

```json theme={null}
{
  "data": {
    "id": "sv03.5",
    "series_id": "sv",
    "name": "151",
    "logo": {
      "low": "https://assets.cromos.so/expansions/sv03-5/logo/low.webp",
      "high": "https://assets.cromos.so/expansions/sv03-5/logo/high.webp"
    },
    "symbol": "https://assets.cromos.so/expansions/sv03-5/symbol/image.webp",
    "palette": ["#0d0b0c", "#fefefd", "#d3aaab", "#e3353a"],
    "release_date": "2023-09-22",
    "card_count_total": 207,
    "card_count_official": 165,
    "legal_standard": false,
    "legal_expanded": true
  },
  "error": null
}
```