Lists are useful because they emphasize selected information in regular text. When you see a vertical list of three or four items instead of a normal paragraph format, you are likely to pay more attention to it. Certain types of lists also support reading and comprehension. In instructions, for example, it’s a big help for each step to be numbered and separate from the preceding and following steps. Lists also create more white space and spread out the text so that pages don’t seem like solid walls of words.

Like headings, the various types of lists are an important feature of professional technical writing. They help readers understand, remember, and review key points. They help readers follow a sequence of actions or events. They break up long stretches of straight text.

Lists fall into two main categories, numbered and bulleted (or whatever visual you want to use instead of the small dots).

General Guidelines for Lists

Follow these guidelines in creating numbered and bulleted lists for technical communications:

• Use lists to highlight or emphasize text or to enumerate sequential items. However, don’t use too many lists, as that destroys their effectiveness.
• Use a lead-in to introduce the list items and to indicate the meaning or purpose of the list. Usually, the lead-in ends with a colon.
• Make sure that each item in the list follows from the lead-in with grammatical correctness.
• Punctuate list items as sentences only if they are, in fact, complete sentences. Otherwise, do not put a period at the end. If list items are not complete sentences, you may, but do not have to, capitalize the first word.
• Be consistent with using initial caps or lower-case letters on the first words of list items.
• Make list items parallel in phrasing. Refer to the page on Sentence Structure in this text for information on parallelism, or search online; there is abundant information on writing sentences using parallel structure.
• Punctuate with a period after the number or letter in a list that shows sequence.
• Choose numbered lists when sequence is important or when you want to emphasize that there are “three main ideas” or “five principles.” Choose bulleted lists when sequence or number is less important.
• Use similar types of lists consistently in the same document.
• When a separate notice or explanatory paragraph follows a item, indent that separate material so that it is not on the same margin as the number, the “parent” item.

Common Problems with Lists

Problems with lists usually include the following:

• Inappropriate choice of numbered vs. bulleted list
• Inconsistent use of similar types of lists within the same document
• Lack of parallel phrasing in the list items
• Run-over lines (list items with second and third lines) not aligned with the text of list items
• Lack of a strong lead-in sentence introducing list items, and lack of a colon to punctuate lead-ins
• Inconsistent caps style in list items
• Unnecessary punctuation of list items
• Inappropriate length – lists that have too many items and need to be subdivided or consolidated

Additional Types of Lists

Two-column, nested, and in-sentence lists are additional types that you may use in technical documents. Each one has its own conventions.

Two-Column Lists

Use two-column lists when you’re comparing characteristics of two items or concepts. Two-column lists highlight the comparison and help condense the length of the document. Note that the general guidelines for lists apply (e.g., introduce the list with a lead-in followed by a colon), along with the following specific guidelines for two-column lists:

• Column headings are optional; if used, align them to the left margin of the text of the columns.
• Left-align the items in both columns.
• Use sentence-style capitalization for both columns.
• Punctuate items in the columns only if they are complete sentences.

Nested Lists

A nested list contains two or more levels of list items—lists and sub-lists. Nested lists can contain different combinations of numbers, bullets, and symbols; choose what makes sense given the content of the list. For example, if you’re listing a sequence within a sequence, use a. b. c. to show sequence in the sub-list for a numbered item in the main list.

Alignment matters with nested lists. Make sure any sub-list aligns with the text of the previous level.

In-Sentence Lists

Sometimes you may not want to use a vertical list if the list is relatively short or if the items fit grammatically, logically, and clearly into one sentence. That’s when you may opt for an in-sentence list. Note, though, that in-sentence lists provide only minimal emphasis; vertical lists provide much more.

Use these guidelines for in-sentence lists:

• Use a colon to introduce the list items only if a complete sentence precedes the list.
  • Incorrect: For this project, you need: paper, scissors, and tape.
  • Correct: For this project you need paper, scissors, and tape.
• Separate the in-sentence list items with commas. Do not incorrectly use semicolons. Use semi-colons in two cases only: 1) if the list items themselves contain commas, or 2) if the list items are short, complete sentences.
• If you need to highlight the items in an in-sentence list, use numbers or lower-case letters with a parentheses after each, such as in the sentence above. Do not use periods after the numbers or letters in an in-sentence list. (That’s where in-sentence lists differ from vertical lists.)
• Place the in-sentence list at the end of the sentence.