Learn English – How to write the date of an event that lasts a few days

When used in reference to time, date almost exclusively refers to a specific 24 hour period that begins at midnight and ends at 11:59pm. When used this way, the date will be specified with a year (CE or BCE), the name of the month, and the number of the day within that month. The day number is a positive whole number that may be used in ordinal form (first, second, third, etc.) The name of the weekday is rarely referenced when referring to a date.

When setting up an appointment, you typically use the term 'date' if the appointment is a long time away or in a formal business setting. When making appointments with friends, especially if they are happening within one week's time, you would use the term 'day'.

You ask a friend "What day do you want to have lunch?" The receptionist at your doctor's office will ask you "What date would you like to have your next appointment?"

Many airlines codify the dates in terms of DDMMMYY but with explicit reference to the month name instead of the month number. For example, your example could be represented as 01JAN23-31DEC86. Depending on the space and the context you could give yourself a some rope and expand the items a little bit. Given the particular nature that in this case both dates belong to another century, you could be a little more specific: 01JAN1923-31DEC1986. If you can spare some more space, maybe some spaces would be fine to make a clearer reading: 01 JAN 1923 - 31 DEC 1986. Another detail could be turning all those caps in month names to normal capitalization, as in 01 Jan 1923 - 31 Dec 1986. You could even drop the leading 0s 1 Jan 1923 - 31 Dec 1986.

On the other hand, I've found this guide on date ranges. The following is just an extract, as there are more considerations when dealing with ranges with different lengths.

Dates of birth and death

At the start of articles on people, their dates of birth and death are provided. For example: "Charles Robert Darwin FRS (12 February 1809 – 19 April 1882) was an English naturalist ..." The two dates are separated by an en dash (HTML code: –). When either date contains a space, the en dash is preceded by a space (preferably a non-breaking space, code:  ) and followed by a space. When full dates are provided in the text or in an infobox, year-pairs can be sufficient for the lede in some cases; in such cases no spaces are used, e.g., "(1943–1971)".

1. For an individual still living: "Serena Williams (born September 26, 1981) ...", not "... (September 26, 1981 –) ..."
2. When only the years are known: "Socrates (470–399 BC) was..."
3. When the year of birth is completely unknown, it should be extrapolated from earliest known period of activity: "Offa of Mercia (before 734 – 26 July 796) ..."
4. When the year of birth is known only approximately: "John Sayer (c. 1750 – 2 October 1818) ..."
5. When the years of both birth and death are known only approximately: "Dionysius Exiguus (c. 470 – c. 540) ..."
6. When the date of death is completely unknown, it should be extrapolated from last known period of activity: "Robert Menli Lyon (1789 – after 1863) ..."
7. When the reign of a sovereign is uncertain: "Rameses III (reigned c. 1180 BCE – c. 1150 BCE) ..."
8. When the individual is known to have been alive (flourishing) at certain dates, [[floruit|fl.]] or {{fl.}} is used in articles, not disambiguation pages, to link to floruit, in case the meaning is not familiar: "Osmund (fl. 760–772) ..."
9. When the individual is known to have been alive as early as about 660, and to have died in 685: "Aethelwalh (fl. c. 660 – 685) ..."

In biographical infobox templates, provide age calculation and microformat compatibility with date mathematics templates. See the documentation for those templates in order to use them properly, and Wikipedia:Manual of Style/Biographies for more guidelines on articles about people.

Other date ranges

Dates that are given as ranges should follow the same patterns as given above for birth and death dates.

Hope it helps.