This article is part of a series about the humble comma, and looks at current practice regarding the comma and such things as addresses, dates and numbers.

Addresses

In days of old, commas were splashed on to envelopes as though they were fairy dust, presumably to get the letter to its proper destination on time and in one piece. These days, style guides such as The Chicago Manual of Style advise us to use commas “sparsely” (CMS’s word) in a mailing address.

I have in front of me a letter that by coincidence was sixty years old the day I posted this article. It has commas just about everywhere in the two addresses on it. Here’s one, reproduced exactly as it is in the letter.

Sister in Charge,
Nurses Home,
144, Longbridge Road,
Barking

The other address has the county (Essex) after the town (Barking), and yes, there’s a comma separating them, and a period (full stop) at the end.

In modern form, that address, even with its postcode added, would require no commas at all.

Sister in Charge
Nurses Home
144 Longbridge Road
Barking IG11 8SP
(Current practice in the UK does not require the county to be included.)

Addresses are less easy to understand in places where roads are numbered, and it becomes even messier when the address includes a suite number, a door/house/building number, a street or avenue number, and a compass point. Despite that abundance of information, current practice is not to separate the elements with commas.

Address in Body of Sentence

When you write an address in textual material, some of the commas from days of old are still required. Here’s a Canadian example.

The Prime Minister’s official residence is 24 Sussex Drive, Ottawa, Ontario K1A 0A3

Address Formats in General

The approved format of addresses is a topic all by itself, and might be the subject of a future article: it’s certainly out of scope for this one. In the meantime, Canadians can learn how to properly address mail at Canada Post’s website. For a more global but less detailed look at addressing formats, Wikipedia’s article is one starting point.

Dates

Dates can be written in seemingly hundreds of different formats. Some require commas; most do not. Date formats are definitely a topic for a future article (especially the confusion caused by the United States’ mm/dd/yy format), but for now we will stick to the current topic—commas.

Here are the most common date formats used in sentence bodies.

The project’s completion will be celebrated on April 30, 2021, with a party. (Comma either side of the year)
The project’s completion will be celebrated on 30 April 2021 with a party. (No comma)

The project completion party will take place on Friday, 30 April 2021 at Gigi’s. (Comma after the day-of-the-week name)

The project completion party will take place on Friday, April 30, 2021, at Gigi’s. (Combination of first and third examples)

The second project is slated for completion in June 2022. (No comma)

Note that four-digit years never take a comma (e.g. 2021, not 2,021). Five-digit and greater years do (e.g. circa 12,500 BCE).

Numbers

The punctuation of numbers varies from country to country (and even within some countries). There are two considerations—the separation of whole numbers from decimal numbers, and the grouping of digits either side of the decimal mark.

In sweepingly general terms, countries influenced by the United Kingdom use the point/period as the decimal mark and group digits using commas, whereas countries influenced by France and other mainland European countries use the comma as the decimal separator and group digits using the point/period.

A list of countries that use each convention can be found in this Wikipedia article.

Canada uses the UK-influenced convention in English and the European-influenced convention in French.

Note that some countries that use the dot/period/point as the decimal mark are adopting the use of the thin space to separate the three-digit groups. This is likely in response to the ISO 30-1 standard that specifies that both the comma and point are reserved as the decimal sign and should therefore not be used to separate groups of digits.

However, the ISO specification of “small” spaces being used to separate groups of three digits might take a little while for some of us to get used to. It might also require an easier way to type a thin space in MS Office; its Unicode point (U2009) appears not to work in amongst numeric digits.

Summary

As you can see, the formatting of addresses, dates and numbers is in flux, largely due, no doubt, to the confusion caused by differing conventions in a global society. The way we learned at school (even relatively recently) is not necessarily the way things are done today.

Where dates are concerned, the changes have been going on for a long time, especially in countries where Anno Domini has no significance. However, that too is outside the scope of this article.

Although the use of commas in all these situations seems, for the most part, to be something that only punctuation pedants would pick up on, it behooves us all to try to adopt current practices—for example, I’m sure that the world’s postal services would like us to punctuate properly. And when using a comma as a decimal mark, its correct use is not merely a pedantic nicety.

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