Items in the catalog which are thought of as having something in common beyond their placement in categories have been grouped together into relationship matches. Several types of these relationships have been defined. For example, in a pair of doors, a left-side door can be matched to a right-side door, and left/right pairing of items is one type of relationship. In another type of relationship, more than one tire may fit on a particular wheel, and the tires and wheels that can fit each other are grouped together in matches based on that commonality.
The following are definitions and explanations of the different relationship types.
|Similar Sets with Same Numbers:|
|These are almost identical sets which may differ on type of packaging, a gear item included in one of the versions, or substantively different stickers. Similar sets with the same number should exhibit distinguishing features on the exterior of the box. An entry with the same number but with a different sequential number is created in these cases.|
|Similar Sets with Different Numbers:|
Differences should include different LEGO package identification numbers, and may include packaging materials, package graphics, some parts or aspects of parts. These things are frequently related to geographic area and time of release.|
Matches may include sets with the same LEGO number, but which are distinguished by different BrickLink suffix numbers, only in cases of three or more set versions, when some have the same LEGO number and some do not.
|Similar Gear with Different Numbers:|
Differences should include different LEGO package identification numbers, and may include packaging materials, package graphics, some parts or aspects of parts. Electronics and video games may include differences in platforms or format. These things are frequently related to geographic area and time of release.|
|Similar Parts with Different Molds:|
The differences recognized are products of variation in mold design or molding process. They include such things as increased strength (various clips thickened), unobtrusive functional additions (hidden axle holders or opened studs), supposed structural improvements for ease of use (altered axle holes).
Does not include cases of variation in the same applied pattern.
Mold versions often accommodate different plastic qualities and dimensional tolerances involving part color. For example, opaque versus transparent plastic for panels, and, chrome and metallic coatings could thicken parts slightly. Changes for this usually involve visible part number differences while the part versions are essentially the same in form and utility. Such differences are recognized on BrickLink with an Alternate Item Number applied to a single catalog entry, rather than with multiple catalog entries within a relationship match. Note that Alternate Item Numbers may be applied for other reasons.
|Same Books in Different Languages:|
Shows books which have essentially the same content but 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:|
|Matches that indicate subtle changes over time to what is essentially the same pattern, applied to what is essentially the same part. As such, different methods of pattern application are also indicated. Does not include changes to pattern colors.|
|Same Stickers with Different Catalog Entries:|
|Because stickers are numbered here according to the set in which they appear, a sticker found in more than one set will have multiple catalog listings.|
|Figure In-Set Variants:|
|LEGO is increasingly allowing variations in design during production of a set. Element colors and patterns may change from one copy of the set to the next. This match type is intended to associate variations which are accepted as intentional production changes or substitutions rather than simple errors.|
|Figure Stickered and Non-Stickered Matches:|
Matches catalog entries for minifigs without sticker(s) applied to catalog entries for otherwise identical minifigs with sticker(s) applied. Set inventories on BrickLink typically list set contents as provided new from the box, unassembled, with the exception of minifigs, which, depending on the viewing option, can be seen as whole items. Since some minifigs are decorated with applied stickers rather than direct printing, and since set inventories include the unused sticker sheet, minifigs with stickers already applied are generally not permitted in the main body of a set inventory. To permit them there would be in effect listing the sticker twice in the inventory. BrickLink recognizes this constraint may complicate searching for stickered minifigs within the catalog when an inventory is used as the starting point.
Stickered minifigs have been permitted in set inventories, in a section of the inventory labeled Counterparts, only since late 2006. There is no automatic correlation of catalog relationship matches and information in set inventories. If you provide a catalog relationship match or a catalog entry designed to enable a match, please provide an inventory counterpart change as well, and vice versa.
|Cross Theme Duplicates:|
|Identical, duplicate, parts are generally not permitted in the catalog but some parts may be hard to find otherwise. This is generally due to the LEGO set 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. In an effort to make such parts findable to all, these do have duplicates here.|
|Door on Door Frame:|
|Shows which doors fit with which door frames. This relationship type does not include just items from the catalog 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 just items from the catalog 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.|
|Some items in the catalog are normally associated with another similar item to make up a left and right pair (for example: 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.|