Guidelines: Item Relationships

Items in the catalog which have something in common beyond their placement in categories have been grouped together into relationship matches. For example, a left-side door can be matched to a right-side door. Left/right pairing of items is one type of relationship. As another example, more than one tire may fit on a particular wheel. Tires and wheels which fit each other are grouped together in matches based on that commonality.

We define and accept submissions for 15 item relationships as shown below. You may add new relationships to existing items or add new items to existing relationships using the Add New Relationship form. You can find relationship numbers for existing relationships and see all item relationships by visiting the Item Relationships page.


Similar Sets with Same Numbers:
These are almost identical sets which differ on type of packaging, an item of gear included in only one of the versions, or substantively different stickers. Similar sets with the same number should exhibit distinguishing features on the exterior of the box.


Similar Sets with Different Numbers:
Differences for this relationship should include different set numbers and may include different packaging materials, package graphics, and some parts or aspects of parts. These differences are frequently related to geographic area and time of release. Matches may include sets with the same set number distinguished by different BrickLink suffix numbers only in cases of three or more set versions, when some have the same set number and some do not.


Similar Gear with Different Numbers:
Differences should include different package identification numbers and may include packaging materials, package graphics, and some parts or aspects of parts. These differences are frequently related to geographic area and time of release. Electronics and video games may include differences in platforms or format.


Similar Parts with Different Molds:
The differences recognized with this relationship type are variations in mold design or molding process. Examples include increased strength, unobtrusive functional additions, and structural improvements for ease of use. This match does not include cases of variation in the same applied pattern or cases of different designed functions, such as Technic pin holes versus Technic axle holes.


Same Books in Different Languages:
Shows books which have essentially the same content, but which were published in different languages. Items numbers are either different for different languages or have a suffix added to distinguish the languages.


Same Items with Different Pattern Style:
These matches indicate subtle changes over time to what is essentially the same pattern which is applied to what is essentially the same part. Different methods of pattern application are included, but this match does not include changes to pattern colors.


Same Stickers with Different Catalog Entries:
Sticker sheets are numbered in the catalog according to the set in which they appear. This match connects stickers found in more than one set which have multiple catalog listings.


Figure In-Set Variants:
This match includes figures which varied in sets with the same set numbers. It is intended to associate variations which are intentional production changes or substitutions rather than simple errors.


Figure Stickered and Non-Stickered Matches:
Matches catalog entries for figures without a sticker or stickers applied to catalog entries for otherwise identical figures with a sticker or stickers applied.


Cross Theme Duplicates:
Matches identical parts from different themes. Identical parts are generally not permitted in the catalog, but some parts may be hard to find otherwise. This is due to themes in which they appear, how they are categorized here as a result, and the degree to which people are likely to be familiar with these themes.


Door on Door Frame:
Shows which doors fit with which door frames. This relationship type does not include only items from the door and door frame categories. It also includes items from other categories which may be considered a door frame in nature, such as a furniture cupboard.


Glass on Window:
Shows which glass fits with which window frames. This relationship type does not include only items from the window and glass categories. It also includes items from other categories which may be considered a window frame in nature, such as a vehicle canopy.


Tire on Wheel:
Shows which tires fit on which wheel hubs.


Paired Parts:
Some items in the catalog are normally associated with another similar item to make up a left and right pair. An example is left and right doors. These parts are not normally attached to each other in any natural way, but are often used together. They are essentially mirror images of each other.


Parts that Belong Together:
Shows parts designed to naturally work with each other which are nearly always used together as a single unit.