Why Does InDesign Think There are 69 days in the Month?

This is a continuation of a post I wrote a couple of years ago: What To Do When InDesign Text Variables Don't Display Correctly

Text Variable Error Type 3: Incorrect Date Format

A client recently wanted to modify the date format used in the footers of her document. So she sent me this to use for the new format: YYYYMMDD.

I pasted this text into the text variable date modification field and resumed editing the document. While I was working, I noticed that the date format ended not in today's date, but in 69. Wait a minute! There  are never 69 days in a month! 

DD looks wrong! There are not 69 days in the month

I thought perhaps this 69 represented some other type of modification data, so I checked the InDesign Help file for what could be represented by DD (as opposed to dd). There was nothing! Out of curiosity, I changed the DD to dd and the date was now correct.

Correct! This file was modified on the 10th of the month

The first time this happened was on March 10. The DD format gave me the number 69. Today (March 11) I opened the file and the DD format gave me 70.

After a little thinking, I looked at my calendar and discovered that today is the 70th day in the calendar year. So I opened up a file that had a different modification date and experimented with the DD variable to see what it gave me.

DD will output the day of the year!

It turns out the DD is actually a variable not documented in the InDesign help file.

Unlike other variables, which can be typed as either uppercase or lowercase, the date format is case sensitive.

• dd will give you the day of the month.
• DD will give you the day of the year.

If your text variables are giving you trouble, please also check out this post on InDesign Secrets: What to Know Before Using Live Captions and Text Variables.