What to Do When One Object Belongs in Three Places
An object can have one practical home and several meaningful relationships. The trick is giving category, theme, and attributes different jobs.
By Akurium
Consider a postcard mailed from the 1933 Chicago World’s Fair.
It is, most plainly, a postcard. It is also World’s Fair material, a piece of Chicago history, an example of commercial printing, a record of travel, and—if the message matters to your family—a personal document.
Where does it belong?
The question can become surprisingly uncomfortable. Choosing one place may feel like denying everything else the object is. Creating a place for every possible interpretation can leave you with an organizational system more complicated than the collection.
The solution is not to discover the object’s single true category.
It is to recognize that different kinds of organization answer different questions.
An object can have one practical home while retaining several meaningful relationships. The trick is to stop asking one category to perform every job.
Classification is a question, not a verdict
Every system of organization emphasizes certain characteristics.
If we arrange postcards by date, we can see change over time. If we arrange them by place, geography becomes prominent. If we group them by printer, production and business relationships appear. If we organize them by subject, the same cards may tell stories about architecture, tourism, advertising, or public events.
The cards remain the same. The question changes.
Large professional vocabularies make this explicit. The Getty Art & Architecture Thesaurus separates concepts into facets such as objects, materials, activities, styles, and physical attributes. A thing may be described through several of these dimensions because “what kind of object is it?” and “what is it made from?” are different questions.
A personal collection does not need a professional thesaurus. It can still benefit from the underlying principle:
Give different kinds of information different jobs.
One useful framework is:
- Category: What kind of thing is it?
- Theme: What larger subject or story brings it into this collection?
- Attributes: What repeatable facts describe this particular example?
- Notes: What context does not fit neatly elsewhere?
These distinctions are not laws of nature. They are tools for preventing one organizational structure from carrying more weight than it can bear.
Give the object one practical home
Physical objects usually need one location.
The postcard cannot simultaneously occupy the postcard box, the World’s Fair cabinet, and the family archive. It must be placed somewhere, even if several locations would make sense.
Digital records often benefit from a primary home as well. One stable placement makes the collection easier to browse and maintain.
Choose that home according to the question you ask most often.
If you usually think, “Where are my postcards?” place it with postcards.
If the collection is specifically about World’s Fair material and includes tickets, souvenirs, programs, photographs, and postcards, the event may be the more useful primary structure.
Neither choice declares what the object truly is. It establishes where you expect to find it.
A practical home is an address, not an identity.
Use categories for kinds of things
Categories are most useful when they describe a relatively stable object type.
Examples might include:
- Postcards
- Cameras
- Matchbooks
- Minerals
- Musical instruments
- Textiles
- Advertising signs
- Printed programs
A good category helps you answer, “What sort of object am I looking at?”
The level of specificity should reflect the collection.
For a broad collection of photographic equipment, “Cameras” may be sufficient. A collection devoted entirely to cameras might need categories such as folding cameras, rangefinders, single-lens reflex cameras, and instant cameras.
Too broad, and the category stops helping. Too narrow, and you may create an elaborate hierarchy containing one object per branch.
Start at the broadest level that still supports the comparisons you want to make. Divide it when repeated differences become useful.
Use themes for the larger story
A theme answers a different question:
What brings these things together here?
The postcard’s category may be “Postcards,” while its theme concerns world’s fairs, Chicago history, travel, or a particular family.
Themes are especially useful when a meaningful group contains different kinds of objects.
A World’s Fair collection might include:
- Postcards
- Tickets
- Souvenir spoons
- Maps
- Photographs
- Guidebooks
- Advertising
- Architectural fragments
Calling all of them “World’s Fair objects” captures their shared subject but obscures their different forms. Categorizing them only by form preserves those distinctions but risks hiding the story that connects them.
Category and theme allow both ideas to remain visible.
Within Akurium, themes establish a broad collecting context, categories describe the kinds of collections within that context, and attributes provide more specific item-level description. That structure is intentionally simpler than a professional polyhierarchy. Its purpose is to make a collection understandable, not to model every possible relationship in the known universe.
Use attributes for repeatable facts
An attribute describes a characteristic of an object.
For the postcard, useful attributes might include:
- Publisher
- Date
- Place depicted
- Printing process
- Dimensions
- Mailed or unused
- Postmark
- Language
- Condition
These facts may help you filter and compare objects, but they do not all need to become categories.
Imagine creating separate categories for:
- Postcards printed in linen finish
- Postcards printed by Curt Teich
- Postcards measuring 3½ by 5½ inches
- Postcards mailed in 1933
- Postcards with edge wear
The same card would belong in all of them, and the category tree would begin repeating the object’s description.
Attributes let the object remain in one practical category while carrying the facts that make it discoverable from other directions.
A useful test is repetition:
Will I record this same kind of information for many objects?
If yes, it may deserve an attribute. If it matters only to one object, a note may be enough.
Put context in notes without apologizing
Not every meaningful fact belongs in a structured field.
The postcard’s message may describe a family event. A pencil annotation may contradict the printed date. The card may have been kept with a train ticket for reasons no one now understands.
These details matter, but forcing them into categories or attributes may make them harder to understand.
Use notes for:
- Stories
- Competing interpretations
- Research questions
- Relationships that need explanation
- Information inherited from a previous collector
- Reasons for uncertain identification
- Exceptions to the usual system
Structure is valuable because it makes repeated information comparable. Prose is valuable because some context cannot survive being reduced to a dropdown menu.
A good catalog uses both.
Be cautious with tags
Tags appear to solve the problem immediately.
Add “Chicago,” “World’s Fair,” “travel,” “architecture,” “family,” and “1930s,” and the object can be found from every direction.
That flexibility is real. So is the possibility of disorder.
Without a little restraint, tags multiply:
- World’s Fair
- Worlds Fair
- World Fair
- world-fairs
- Expositions
- Chicago Expo
What looks like rich description becomes six near-synonyms that divide search results.
Before creating a tag, ask:
- Will I use it again?
- Does an existing term mean the same thing?
- Is this a subject, an object type, or a fact better stored elsewhere?
- Would a reader understand what this tag includes?
Controlled vocabularies exist partly to keep equivalent ideas from scattering under inconsistent terms. A personal collection does not need Library of Congress Subject Headings, but it does benefit from deciding whether “automobiles” and “cars” are one concept or two.
Use the language that feels natural. Then use it consistently.
Accept that some objects have several parents
Even highly developed professional vocabularies encounter objects and concepts that belong in more than one hierarchy. The Getty describes its Art & Architecture Thesaurus as polyhierarchical: a concept may have more than one broader parent.
That does not mean your collection system must reproduce this complexity.
It does mean the discomfort you feel when an object fits several places is not evidence that you have failed to understand it. Some relationships genuinely overlap.
When your system allows only one primary category:
- Choose the most useful home.
- Preserve other relationships through themes, attributes, notes, or cross-references.
- Record why the decision was difficult if that difficulty contains useful information.
The goal is not to remove ambiguity from the object. It is to keep ambiguity from making the object impossible to find.
Let the system change after meeting the collection
Many organizational systems are designed in the abstract and defeated by the fourth object.
That is normal.
A category that seemed obvious may prove too broad. Two categories may turn out to be indistinguishable in practice. An attribute may matter for five objects and never appear again. A miscellaneous group may quietly develop enough internal coherence to earn a name.
Revise the system when patterns emerge.
Useful changes include:
- Renaming a category in the language you actually use
- Merging categories that answer the same question
- Dividing a category when it has become difficult to browse
- Turning a repeated note into an attribute
- Moving a fact out of a category and into metadata
- Preserving an old term as a synonym when appropriate
Revision is not a sign that the first system failed. It is evidence that the collection taught you something.
Organize for return
The final test of a classification system is not whether its diagram looks elegant.
Ask instead:
- Can I find the object?
- Can I understand why it belongs here?
- Can I recover its important relationships?
- Can I compare it with similar objects?
- Can another person make sense of the language?
- Can the system change without collapsing?
Return to the postcard.
Give it one practical home. Call it a postcard. Connect it to the World’s Fair story. Record its publisher, date, process, and postmark. Preserve the family message in notes.
Nothing important has been denied. The object has not been forced to choose one identity. Each part of the system is simply doing its own work.
An object can belong in three places because “belonging” has more than one meaning.
Suggested further reading
- The Getty Vocabulary Program’s guidance on hierarchical relationships explains facets, broader and narrower concepts, physical attributes, and polyhierarchy.
- The Library of Congress provides an overview of its controlled vocabularies used for consistent subject access.