---
title: objectclasslookup - X4 schema type
summary: objectclasslookup: X4 attribute schema type: base types, constraints and value alternatives.
section: reference
kind: guide
status: reference
updated: 2026-10-27
tags: ["XSD","schema","types"]
sources: ["https://wiki.egosoft.com/X4%20Foundations%20Wiki/Modding%20Support/","https://www.w3.org/TR/xmlschema11-2/"]
---
## Meaning

objectclasslookup: X4 attribute schema type: base types, constraints and value alternatives.

An XSD type constrains XML, rather than declaring a Lua return or the payload type of event.param. A valid schema value does not prove a successful game effect.

## Schema structure

`libraries/common.xsd`

| Property | Value |
| --- | --- |
| Construction | `union` |
| Union members | [`shipclasslookup`](wiki:schema-shipclasslookup-73b4e416), [`stationclasslookup`](wiki:schema-stationclasslookup-677e657d), [`expression`](wiki:schema-expression-b8bc0e4f) |

Additional inline union branch:

| Property | Value |
| --- | --- |
| Construction | `restriction` |
| Base type | [`xs:string`](wiki:schema-xs-string-d5652e9b) |

| Constraint | Value |
| --- | --- |
| `enumeration` | `class.adsignobject` |
| `enumeration` | `class.asteroid` |
| `enumeration` | `class.bomb` |
| `enumeration` | `class.checkpoint` |
| `enumeration` | `class.collectable` |
| `enumeration` | `class.container` |
| `enumeration` | `class.controllable` |
| `enumeration` | `class.datavault` |
| `enumeration` | `class.defensible` |
| `enumeration` | `class.drop` |
| `enumeration` | `class.explosive` |
| `enumeration` | `class.gate` |
| `enumeration` | `class.highwayentrygate` |
| `enumeration` | `class.highwayexitgate` |
| `enumeration` | `class.lockbox` |
| `enumeration` | `class.mine` |
| `enumeration` | `class.missile` |
| `enumeration` | `class.navbeacon` |
| `enumeration` | `class.nebula` |
| `enumeration` | `class.object` |
| `enumeration` | `class.recyclable` |
| `enumeration` | `class.resourceprobe` |
| `enumeration` | `class.satellite` |

restriction narrows a base type; union accepts one of its branches; list describes whitespace-separated items. Enumeration values in one restriction are alternatives. Pattern syntax is XML Schema regex, not Lua patterns or JavaScript RegExp. Constraints inherited from the base type still apply.

## Example and result

Use the attribute pages below for contextual examples. A generic executable example is not inferred from a type name alone.

## Used by

| Element | Attribute | Schema |
| --- | --- | --- |
| [`find_object`](wiki:api-md-find-object-573637c1) | `class` | `libraries/common.xsd` |
| [`find_object`](wiki:api-md-find-object-573637c1) | `exactclass` | `libraries/common.xsd` |


[All schema types](wiki:schema-types) · [Lua / MD value types](wiki:types)