Common Vocabulary Translator

The Common Vocabulary Translator (CVT) is a software program that translates the nearly 15,000 Nomenclature 4.0 terms into the simpler Common Vocabulary terms used in the Digital Archive. It also adds additional terms to the Common Vocabulary that do not exist in Nomenclature.

This page explains:

Advanced Topic

This information is for anyone who wants to know how the Common Vocabulary gets created, but it is written for someone who will be working with the CVT software and therefore is fairly technical.


To understand the CVT, become familiar with the terminology below.

Nomenclature hierarchy

The Nomenclature term hierarchy can be up to six levels deep, though not every term uses all six levels. The levels are shown below, but note that Nomenclature uses the word term to mean both the entire term and each of the last three levels of the complete term. This can be confusing which is why this documentation only uses term to mean the entire set of words for a complete term. It refers to the last three levels of a complete Nomenclature term as the Primary, Secondary, and Tertiary parts.

1  Category
2  Class
3  Sub Class
4  Primary term
5  Secondary term
6  Tertiary term

Here are three examples of Nomenclature terms:

Category 01: Built Environment Objects
    Building Components
        Construction Materials
            Building Stone
                Dimension Stone
                    Dressed Stone

Category 07: Distribution & Transportation Objects
    Land Transportation T&E
        Animal-Powered Vehicles

Category 08: Communication Objects
    Documentary Objects
        Graphic Documents

Common Vocabulary hierarchy

The CVT translates Nomenclature terms into simpler Common Vocabulary terms based on a set of translation rules that will be explained later. The rules tell the CVT how to translate the terms shown in the previous section into the terms shown below.

Object, Building Stone, Dimension Stone, Dressed Stone

Transportation, Carriage, Buckboard

Image, Photograph, Negative

As you can see, Common Vocabulary terms are typically much simpler and easier to read than Nomenclature terms. In fact, approximately 95% of Common Vocabulary terms have four or fewer levels in their hierarchy. Only about 5% have five levels and none have six.


Leaf means the words at the deepest level in a hierarchy. In examples in both sections above, the leaf words are: Dressed Stone, Buckboard, and Negative. The CVT preserves Nomenclature leaf words to ensure that they are the same as, and can be matched with, the same leaf words used in other collection software, like PastPerfect, that uses Nomenclature.

Nomenclature 4.0 supports leaf words in both inverted and natural order. Examples of each follow.

Inverted Order Natural Order
Negative, Glass Plate Glass Plate Negative
Negative, Roll File Roll Film Negative
Negative, Sheet Film Sheet Film Negative

The Common Vocabulary uses natural order because it's easier to read.


Commas are not allowed in Common Vocabulary leaf words because comma is reserved as a hierarchy level indicator. This is particularly important in place names where comma is a commonly used separator. So for example, in the Common Vocabulary use Bangor ME as the leaf, not Bangor, ME.


Tail is a CVT term used in the translation rules. The tail consists of a Nomenclature term's Primary, Secondary, and Tertiary parts, if all three exist. If a term has no Tertiary part, the tail consists of the Primary and Secondary parts. If a term has no Secondary part, the tail is just the Primary part. Some higher level terms have no Primary part, but still have a leaf which is either the Sub Class or Class part. In those cases, the tail and the leaf are the same.

Translation rationale

The purpose of the Common Vocabulary is to fulfil the need for a rich, practical, and easy to read set of vocabulary terms that archivists can use in cataloging collections which not only contain physical objects like those found in museums, but also contain items about people, places, structures, events, and organizations.

Nomenclature has thousands of terms for naming human-made objects, but none for things like plants or animals, businesses or organizations, or places like towns and villages. Object names alone are not sufficient for cataloging many Digital Archive items, especially Reference Items which serve as stand-ins for real-world entities like people, boats, and houses.

While Nomenclature by itself does not fill the need, it does provide the hierarchical organization, and most of the leaf words, used by the Common Vocabulary.

The rationale for how Nomenclature gets translated to Common Vocabulary, is provided in the following sections.

Common Vocabulary Type and Subject

Before continuing, it is important to explain the proper use of, Type and Subject. Note that throughout this documentation, when the words Type and Subject appear in small caps, they refer to an item's Type and Subject metadata fields.

Every item must have a Type – there are no exceptions.

Every item must also have a Subject except in certain cases which are explained below. The Subject is required to further classify the Type. For example, an item of Type Image, Photograph must have a Subject to indicate the nature of the picture since Photograph alone is too vague. For example, the subject of a photograph could be People to indicate that it's a photo of humans.

When a Subject is optional

When an item's Type begins with Object, a Subject is not required, meaning that you can save the item without choosing a Subject. For example, an item with Type Object, Cup, Teacup needs no further classification and requires no Subject. However, the Type Object, Art, Sculpture, Carving is vague and so a Subject likeNature, Animals, Birds is recommended.

When a Subject is required, but not needed

The rule that a Subject is required unless the Type begins with Object works well in general, but there are some non-object types that are self-evident and don't need a Subject. For example Type Document, Log, Ship's Log doesn't need further classification, but if you omit the Subject, you'll get an error when you attempt to save the item. In that case, you can choose the special Subject none to override the requirement for a Subject so that you can save the item. Note that whenever you edit that item, you'll have to choose none again to save it. That's because the item gets saved without a Subject – the Subject is not getting set to none. Use this feature judiciously.

Top level types and subjects

The table below shows the top level Type and Subject terms in the Common Vocabulary.

Type Subject
Document Businesses
Image Events
Map Nature
Object Object
Publication Organizations
Reference Other
Set People

Archivists at the Southwest Harbor Public Library derived the terms based on four years working with the collections of cultural heritage organizations on Mount Desert Island in Maine. Together, the collections contain more than 20,000 items, nearly 25,000 images, and over 3,000 documents. They chose simple words that a) reflect the focus of the collections and b) have obvious meaning. While the choices are subjective, they are meeting the cataloging needs of many organizations.

Top level translations

The table below gives a general sense of which Nomenclature Categories translate to which Common Vocabulary top level terms. To see how specific Classes, Subclasses, and individual terms translate, you can look at the translation rules that the CVT follows.

Nomenclature Category Common Vocabulary
Category 01: Built Environment Objects All translate to Object except for terms with Nomenclature Class Structures which translates to Subject Structures and to Type Object, Structures
Category 02: Furnishings All translate to Object
Category 03: Personal Objects All translate to Object
Category 04: Tools & Equipment for Materials All translate to Object
Category 05: Tools & Equipment for Science & Technology All translate to Object
Category 06: Tools & Equipment for Communication All translate to Object except Picture Postcard which translates to Image
Category 07: Distribution & Transportation Objects All translate to Object except for transport vehicles like cars, boats, and trains which are translated to Subject Transportation or Vessels and to Type Object, Transportation or Object, Vessels
Category 08: Communication Objects Most translate to Document, Image, Map or Publication unless they are none of those, in which case they translate to Object.
Category 09: Recreational Objects All translate to Object
Category 10: Unclassifiable Objects All translate to Object

Note: Although vessels are a form of transportation, Vessels is elevated to a top level Subject term because boats and ships are so prominent in the collections of coastal communities.

Rationale for how Nomenclature terms get translated

There are many ways that Nomenclature could be morphed into a Common Vocabulary.
Here is an explanation of, and the reasoning behind, the way the CVT does it.

Type vocabulary

All Nomenclature terms are translated to the Type vocabulary. In other words, every term in Nomenclature can be found in the Type vocabulary.

The top-level terms Structures, Transportation, and Vessels are included in the Type vocabulary as
sub-types of Object (e.g. Object, Structures) so that they are not top-level Type terms which would be rarely used in most collections. They are however top-level terms in the Subject vocabulary. For instance, most collections won't have any items of type Transportation, Automobile, but many will have photograph or document items having the Subject Transportation, Automobile. If a collection does contain a car, the item's Type would be Object, Transportation, Automobile.

Subject vocabulary

Many, but not all Nomenclature terms are also translated to the Subject vocabulary.

Translated: Nomenclature terms for physical, three dimensional objects, are translated to the Subject vocabulary.

Not translated: Objects that are more or less two dimensional are not translated to the Subject vocabulary. They are translated to the Type vocabulary as Document, Image, Map, or Publication.


Terms for physical objects become both Type and Subject terms because collections generally have either an actual object such as a hat, or they have a photograph of, or documents about, an object such as a picture of a person wearing a hat.

For an actual hat that's in the collection, the item's Type would be Object, Clothing, Hat with no Subject. For a photograph of someone wearing a hat, the item's Type would be Image, Photograph and the Subjects would be People and Object, Clothing, Hat.

The idea is that terms used to classify a physical object can usually be used for either Type or Subject (but not both) depending on whether it's a physical item is in the collection (Type) or if the item in the collection depicts, or is about, the item (Subject).

Terms not in Nomenclature

Terms for things like people, animals, businesses, organizations, and events that do not exist in Nomenclature, have been added to the Subject vocabulary.

Terms for the names of towns and villages are in the Place vocabulary.

The term Reference has been added to the Type vocabulary. Learn about Reference Items.

The term Set has been added to the Type vocabulary. Learn about Item Sets.

To see exactly what non-Nomenclature terms the CVT adds to the Common Vocabulary, you can look at the additional terms file which tells the CVT what terms to add.

Translation process

This section explains how the CVT actually performs the translation from Nomenclature terms to Common Vocabulary terms. In the diagram below, the black box in the middle represents the CVT software. The boxes in the top row represent data files that the CVT reads, and the boxes in the bottom row represent data files that the CVT creates.

CVT diagram

Translation Rules

The translation rules are contained in a translations file which is a spreadsheet of rows and columns in CSV format. Each row in the translation tables defines one translation rule.

Every rule column is optional except for Category and Translation. If the Category or Translation columns is blank, the CVT ignores the entire row. This allows you to place blank rows between groups of rules.

The CVT processes terms in the Nomenclature file one at a time to translate them into corresponding terms in the Common Vocabulary file. For each Nomenclature term, the CVT looks for a matching translation rule by starting with the first rule in the translation file, and going to the next rule, until it finds a match.

The CVT ignores Nomenclature rows having a level column value of 1 or 2 because those rows have no leaf words and therefore do not represent a Nomenclature terms. A level 1 row only has a Category value. A level 2 row has a Category and a Class.

To find a matching rule, the CVT interprets each rule by comparing the rule's A - F column values, from left to right, against the corresponding values from the Nomenclature row being processed. If every non-blank rule column value matches the corresponding Nomenclature row value, the CVT applies the rule, otherwise it skips to the next rule. The CVT only applies one rule to a row (it does not keep looking for matching rules once it finds the first match).

Important: More restrictive rules must occur in the translation file above less restrictive rules, otherwise, the CVT will apply a less restrictive rule before it encounters a more restrictive rule. For example, a rule that applies to any Nomenclature row having a certain Class, must appear after a more restrictive rule that applies only to rows of that Class that have a specific Sub-class or Primary part.

Translation rule columns

The table below explains each of the translation rule columns.

Column Name Usage
A Category Match a value from the Nomenclature Natural_Order_EN_Category column
B Class Match a value from the Nomenclature Natural_Order_EN_Class column
C Sub_Class Match a value from the Nomenclature Natural_Order_EN_Sub_Class column
D Primary Match a value from the Nomenclature Natural_Order_EN_Primary_Term column
E Secondary Match a value from the Nomenclature Natural_Order_EN_Secondary_Term column
F Identifier Match a value from the Nomenclature Identifier column. Use this column when the rule should only apply to a single Nomenclature term.
G Translation A pattern specifying the Common Vocabulary term. The pattern contains one or more of the substitution elements explained in the next section.
H Replace Zero or more pairs of values in double quotes, separated by a comma, specifying before and after values. the CVT applies the replacement to the translated text after performing the translation.
J Notes Comments (ignored by the CVT)

As an example, if a rule's Replace column contained the pair "Lodging Facility", "Lodging",
matching the term Structures, Commercial, Lodging Facility, Hotel, the term would get changed to Structures, Commercial, Lodging, Hotel.

Substitution Elements

The Translation column of a translation rule must contain one or more of the following substitution elements:

Substitution Meaning
{class} The value of the Natural_Order_EN_Class column of the Nomenclature row. Used when the Nomenclature class should be included as-is in the resulting Common Vocabulary term.
{sub_class} The value of the Natural_Order_EN_Sub_Class column of the Nomenclature row. Used when the Nomenclature sub class should be included as-is in the resulting Common Vocabulary term.
{tail} The tail of the Nomenclature term. Used for most rules.
{leaf} The leaf of the Nomenclature term. Used instead of {tail} only when the tail value contains more levels of information than are necessary for the resulting Common Vocabulary term.

The {tail} and {leaf} elements are mutually exclusive and so only one or the other should be used. These two terms are only ever used at the end of the translation text.

Examples of rules in the Translation column:

Object|Tools & Equipment|{class}|{tail}

Translation Process

The CVT processes one Nomenclature row at a time. When the CVT finds a matching rule for a row, it applies the rule to the row as follows:

  1. Perform the substitutions listed in the table above
  2. Make any replacements specified in the Replace column
  3. Emit the resulting string as the Common Vocabulary term

Translation software

The CVT is implemented as a Python program that was developed by George Soules of AvantLogic Corporation. The source code and data files are available as open source in the AvantCommonVocabulary repository on GitHub.

Input Files

The program reads these files from the /data folder located in the Python script's folder.


Outputs Files

The program creates these files in the /data folder located in the Python script's folder.
It also uploads the files to

  • The digital-archive-diff.csv will contain update instructions if the CVT found differences between input-previous-digital-archive-vocabulary and the newly created digital-archive-diff.csv. Learn how to apply the updates to Digital Archive sites.

  • If input-previous-digital-archive-vocabulary does not exist as an input file:

    • digital-archive-diff.csv will be empty because there can be no differences without a previous vocabulary to compare to.
    • The CVT will create a new copy of input-previous-digital-archive-vocabulary.csv (the dashed line in the CVT diagram above) by copying the newly generated
      digital-archive-vocabulary.csv file.
Nomenclature data

To get the latest version of Nomenclature 4.0:

  1. Download it as an Excel file from
  2. Open the .xlsx file and save it as a CSV file
  3. If Excel displays a We found a problem error, click YES to recover the file
  4. Save the file as CSV UTF-8
  5. Delete the .xlsx file since it's no longer needed

To compare old and new versions of Nomenclature using the Beyond Compare program,
do a text compare, not a table compare.