Lists — how and when to use them

 

Graphic showing an itemised tick listNot sure how to write high-quality lists or when to use a list?
Confused about punctuation and capitalisation of lists?

This page answers those questions and shows you how to use a list to capture your reader’s attention.

 

 

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Definition

 

A list is a record that consists of an introductory statement and a a series of items written one after another. The list can be presented vertically or horizontally.

In a vertical list, the items are on separate lines. In a horizontal list, the items are part of the sentence and follow the introductory statement.

Lists: vertical versus horizontal list

Comparing a vertical list to a horizontal list

 

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Vertical lists

I am a great fan of vertical lists. They are the best tool to make important information stand out on the page, show the steps in a process, or present an overview to the reader. Lists are therefore extremely useful in reports, technical and scientific documents, and online.

When to use a vertical list?

In non-fiction writing, vertical lists are an important tool for the writer. A vertical list can be extremely useful when you want to draw the reader’s attention to certain important points.

Use a vertical list when you want to:

  • make the reader memorise something
  • group information or give the reader an overview of something
  • show an order, hierarchy or chronology
  • make the reader follow ordered instructions.

A vertical list is much easier to read and scan than a paragraph because it visually breaks up long sections of text and creates white space. It stands out on the page and helps the reader find information quickly, thus improving the usability of a document.

Vertical lists are therefore often found in non-fiction documents such as manuals, procedures and guidelines, self-use instructions and cook books, reports, online content and blogs.

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Types of vertical lists

Lists can be unordered or ordered, simple or multilevel. Below, I show examples and when they can be used.

The unordered list is the most commonly used list. You can use it to draw special attention to certain elements you want the reader to remember.

Example — a simple unordered list

For the Australian region, the main drivers of natural climate variability are the:

  • El Niño–Southern Oscillation
  • Indian Ocean Dipole
  • Madden–Julien Oscillation
  • Southern Annular Mode.

Ordered lists are useful when you need to show a chronological sequence of events, or steps in a process.

Example — a simple ordered list

The four steps of the scientific method are:

  1. observe and describe a phenomenon
  2. formulate a hypothesis
  3. test the hypothesis
  4. establish a theory based on repeated validation of results.

You can also use an ordered list when you intend to cross-reference to the items in subsequent paragraphs.

Example — a simple ordered list

There were four testing sites for water quality:

  1. downstream of the lake
  2. the northern part of the lake
  3. the southern part of the lake
  4. upstream of the lake.

Sections a and b showed good water quality, but sections c and d were below standard.

You can use a multilevel list to bring clarity and show overview in complex information. The following example has two levels.

Example — an unordered multilevel list

Fish species currently prescribed as threatened under the Nature Conservation Act 2014 in the ACT are:

  • endangered species
    • Macquarie Perch (Macquaria australasica)
    • Silver Perch (Bidyanus bidyanus)
    • Trout Cod (Maccullochella macquariensis)
  • vulnerable species
    • Murray River Crayfish (Euastacus armatus)
    • Two-Spined Blackfish (Gadopsis bispinosus).

However, I do not recommend using more than three levels. Using lists that are too complex may confuse the reader.

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How to punctuate and capitalise a vertical list?

This section shows you a quick way to work out punctuation and capitalisation in vertical lists.
Steps include:

  1. write the list as normal text
  2. convert the list to a vertical format
  3. adjust the punctuation and capitalisation.

In the following examples, I show how to use this method for list items that are words or groups of words, part-sentences, full sentences, or other lists.

1. Write the list as normal text

Example — words or groups of words

To make a cup of tea you need a cup, a tea bag, and hot water.

2. Convert the list to a vertical list format.

You can quickly convert the text to a list by separating the introductory statement from the list, adding a colon, and retaining punctuation and capitalisation.

Example — words or groups of words

To make a cup of tea you need:

  • a cup,
  • a tea bag, and
  • hot water.

In the above example, commas separate the list items. The second-last item retains ‘, and’ at the end, while the last item retains the full stop.

3. Adjust punctuation and capitalisation.

Remove the comma and the ‘, and’ at the end of the item lines. This is not essential, but makes the list easier to read.

Example — words or groups of words

To make a cup of tea you need:

  • a cup
  • a tea bag
  • hot water.

I recommend using this style.

Many lists consist of more or less complex part-sentences. Part-sentences need extra care when itemising to make sure the list does not become ambiguous.

1. Write the list as normal text.

Example — part-sentences

The museum’s role is to look after the state’s collection; create exhibitions on the state’s past, present and future; and contribute to historical research programs.

2. Check parallel structure.

Before converting to a vertical format, make sure all list items are parallel. Each part-sentence has to make a full sentence when read after the introductory statement. For more details on how to check parallel structure, see How to ensure parallel structure in a list?.

Example — check parallel structure of part-sentences

The museum’s role is to look after the state’s collection.

The museum’s role is to create exhibitions on the state’s past, present and future.

The museum’s role is to contribute to historical research programs.

3. Convert the list to a vertical format.

Example — part-sentences

The museum’s role is to:

  • look after the state’s collection;
  • create exhibitions on the state’s past, present and future; and
  • contribute to historical research programs.

4. Adjust punctuation and capitalisation.

Remove the semicolon and the ‘; and’ at the end of the item lines. This is not essential, but makes the list easier to read.

Example — part-sentences

The museum’s role is to:

  • look after the state’s collection
  • create exhibitions on the state’s past, present and future
  • contribute to historical research programs.

I recommend using this style.

Lists of full sentences are useful to show structure as you write. They help the reader understand the text, and also create some white space in what would otherwise be solid text.

1. Write the list as normal text.

Example — full sentences

The report of the Intergovernmental Panel on Climate Change lists the following key climate changes. Each of the past three decades has been successively warmer at Earth’s surface than any preceding decade since 1850. In the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the past 1400 years. Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010. It is virtually certain that the upper ocean (0–700 m) warmed from 1971 to 2010, and it is likely that it warmed between the 1870s and 1971. During the past two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent.

2. Convert the list to a vertical list format.

Choose the introductory sentence carefully before converting. In the example, the introductory sentence could end with a colon or a full stop.

Example — full sentences

The report of the Intergovernmental Panel on Climate Change lists the following key climate changes:

  • Each of the past three decades has been successively warmer at Earth’s surface than any preceding decade since 1850. In the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the past 1400 years.
  • Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010. It is virtually certain that the upper ocean (0–700 m) warmed from 1971 to 2010, and it is likely that it warmed between the 1870s and 1971.
  • During the past two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent.

3. Adjust punctuation and capitalisation.

If each list item is a full sentence, there will be no further need to adjust the punctuation or capitalisation of the list. Each full sentence starts with a capital and ends with a full stop.

There are many combinations of multilevel lists and their punctuation can be hard to work out. When creating complex lists, always make sure that the structure is logical and items are parallel.

1. Write the list as normal text.

Example — multilevel lists

Fish species currently prescribed as threatened under the Nature Conservation Act 2014 in the ACT include endangered species and vulnerable species.

Endangered species are native species eligible to be included in the endangered category on the threatened native species list if not critically endangered, but facing a very high risk of extinction in the wild in the near future.

Endangered fish species include Macquarie Perch (Macquaria australasica), Silver Perch (Bidyanus bidyanus), and Trout Cod (Maccullochella macquariensis).

Vulnerable species are native species eligible to be included in the vulnerable category on the threatened native species list if not critically endangered or endangered, but facing a high risk of extinction in the wild in the medium-term future.

Vulnerable fish species include Murray River Crayfish (Euastacus armatus) and Two-Spined Blackfish (Gadopsis bispinosus).

2. Convert the list to a vertical list format.

Example — multilevel lists

Fish species currently prescribed as threatened under the Nature Conservation Act 2014 in the ACT include endangered species and vulnerable species:

  • Endangered species are native species eligible to be included in the endangered category on the threatened native species list if not critically endangered, but facing a very high risk of extinction in the wild in the near future. They include
    • Macquarie Perch (Macquaria australasica),
    • Silver Perch (Bidyanus bidyanus), and
    • Trout Cod (Maccullochella macquariensis).
  • Vulnerable species are native species eligible to be included in the vulnerable category on the threatened native species list if not critically endangered or endangered, but facing a high risk of extinction in the wild in the medium-term future. They include
    • Murray River Crayfish (Euastacus armatus) and
    • Two-Spined Blackfish (Gadopsis bispinosus).

Note that a colon is only used at the end of the first introductory statement and not for the second-level introductory statement.

3. Adjust punctuation and capitalisation.

As shown in the previous sections, remove comma and ‘, and’ from the end of item lines. In some cases, repeated text can also be removed at this stage.

Example — multilevel lists

Fish species currently prescribed as threatened under the Nature Conservation Act 2014 in the ACT include endangered species and vulnerable species:

  • Endangered species are native species eligible to be included in the endangered category on the threatened native species list if not critically endangered, but facing a very high risk of extinction in the wild in the near future. They include
    • Macquarie Perch (Macquaria australasica)
    • Silver Perch (Bidyanus bidyanus)
    • Trout Cod (Maccullochella macquariensis).
  • Vulnerable species are native species eligible to be included in the vulnerable category on the threatened native species list if not critically endangered or endangered, but facing a high risk of extinction in the wild in the medium-term future. They include
    • Murray River Crayfish (Euastacus armatus)
    • Two-Spined Blackfish (Gadopsis bispinosus).

Note that a colon is only used at the end of the first introductory statement and not for the second-level introductory statement.

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How to check a vertical list?

Once you have created your list, use the following checklist to make sure it will be of high quality:

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Horizontal lists

A list that appears in a sentence is called a horizontal list or a run-in list (sometimes also referred to as an in-line list).

When to use a horizontal list?

Horizontal lists are useful if you do not have space to create a vertical list or if you do not wish to visually interrupt the flow of the text. To make a horizontal list easier to read, keep it short. I suggest you do not list more than four or five items.

Example — simple unordered horizontal list

Example To make a cup of tea, you need a tea bag, a cup and hot water.

To avoid ambiguity, carefully choose the placement of the list in the sentence.

Example — incorrect placement of a horizontal list

You will need the following items: a cup, hot water and a tea bag to make a cup of tea.

Reword the list to remove the ambiguity.

Example — correct placement of a horizontal list

You will need the following items to make a cup of tea: a cup, hot water and a tea bag.

In situations where the list is long or complex, using a vertical list may be a better option.
See also Vertical lists.

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How to punctuate a horizontal list?

To separate items that are words or groups of words, use a comma.

Example — list items are words or groups of words

The aims of this program are to support excellence, promote access to training, and protect non-profit organisations.

See also When to use a comma before ‘and’ or ‘or’ in a list?

For items that already contain a comma or are full sentences, separate the list items using a semicolon.

Example — list items are part-sentences with a comma, or full sentences

The museum has stewardship of the state’s collection; creates exhibitions on the state’s past, present and future; and contributes to historical research programs.
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How to order a horizontal list?

If your horizontal list is also ordered, you can use numbers or letters to clarify the order. Make sure these numbers or letters stand out clearly from the list items by adding brackets.

Example — an ordered horizontal list using numbers

To make a cup of tea: (1) place a tea bag inside a cup; (2) fill the cup with hot water; and (3) let it brew until it has the desired strength.

Example — an ordered horizontal list using letters

To make a cup of tea: (a) place a tea bag inside a cup; (b) fill the cup with hot water; and (c) let it brew until it has the desired strength.
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When to use a comma before ‘and’ or ‘or’ in a list?

The serial comma (also called the Oxford comma or Harvard comma) is the comma that occurs before the ‘and’ or ‘or’ at the end of a horizontal list with at least three items.

It is best to use the serial comma if it will remove potential ambiguity.

Example — ambiguity in a horizontal list

I dedicate this book to my parents, Bob James and Mary Higgins.

In the above example, it is not clear if the dedication is to four people (my parents and Bob James and Mary Higgins) or if my parents are Bob James and Mary Higgins. Adding the serial comma removes this ambiguity.

Example — use the serial comma to remove ambiguity

I dedicate this book to my parents, Bob James, and Mary Higgins.

If not required for removing ambiguity, using the serial comma is a matter of choice. However, many organisations use the serial comma and have this as a requirement in their style guide; so, always check!

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How to ensure parallel structure in a list?

Parallel structure ensures that the wording of the list items is consistent. This makes it much easier for the reader to understand the list, especially when the list items are part-sentences.

Parallel structure is often lost when the writer tries to amalgamate information from different sources into a single list.

Both vertical and horizontal lists need to be parallel. I use a vertical list in the example below, but the same method can be applied to fix horizontal lists.

Example — incorrect parallel structure

The organisation’s web publishing requirements are:

  • Start file names with the document identification number.
  • Heading styles must be applied in the correct hierarchy.
  • Only use provided styles, plus italics.
  • Hyperlinks to be noted using comments.
  • All images and diagrams must be accompanied with descriptive alternative text.

In the above example, parallel structure is lost. Some of the items are part-sentences, other items are full sentences.

To fix the parallel structure, rewrite the introductory statement so it will form a complete sentence with the first part-sentence items in the list.
Then, place the introductory statement before each of the other list items, as follows.

Example — test parallel structure

The organisation’s web publishing requirements are to: Start file names with the document identification number.

The organisation’s web publishing requirements are to: Heading styles must be applied in the correct hierarchy.

The organisation’s web publishing requirements are to: Only use provided styles, plus italics.

The organisation’s web publishing requirements are to: Hyperlinks to be noted using comments.

The organisation’s web publishing requirements are to: All images and diagrams must be accompanied with descriptive alternative text.

By doing this, you can immediately see the problems with the list: it does not have a parallel structure.

To fix the structure, reword each list item so it forms a complete sentence with the introductory statement. This also shows that the capitals after the colon can be removed.

Example — fix parallel structure

The organisation’s web publishing requirements are to: start file names with the document identification number.

The organisation’s web publishing requirements are to: apply heading styles in the correct hierarchy.

The organisation’s web publishing requirements are to: use provided styles only.

The organisation’s web publishing requirements are to: note hyperlinks using comments.

The organisation’s web publishing requirements are to: provide descriptive alternative text for all images and diagrams.

Then, rewrite the text as a list (i.e. move the introductory statement to the start) and apply list punctuation to the list items (i.e. remove the full stop at the end of the items, except the last one).

Example — parallel structure

The organisation’s web publishing requirements are to:

  • start file names with the document identification number
  • apply heading styles in the correct hierarchy
  • use provided styles only
  • note hyperlinks using comments
  • provide descriptive alternative text for all images and diagrams.

Once made parallel, the list is much easier to read. It is now also easier to edit.

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Good luck with creating lists!
Leave a comment or ask a question below if you have any other issues you would like me to discuss here.

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