How to build a sourced timeline

Step 1: decide what kind of date each entry is

Before you write any date down, decide what it measures. A Form 8-K has a Date of Report, which is the date of the earliest event reported ¹. It has a filing date set by EDGAR rules, and a transmission after 5:30 p.m. Eastern counts as filed on the next business day ². These are two entries, or one entry with two labelled dates.

Use the same care for laws and statistics. An EU act can have a date of document, a date of entry into force and a later date of application. A statistic has a reference period and a release date. The date terms tool on this site lists these types with sources.

Step 2: write dates in one standard form

Store each date as YYYY-MM-DD. The W3C profile of ISO 8601 allows YYYY-MM and YYYY, so a source that gives only a month can be stored as, for example, 1997-07 ⁴. Do not add a day the source does not give.

Where a source gives a time, keep the time zone. A designator of Z means UTC, and an offset such as -05:00 shows the gap from UTC ⁴. RFC 3339 adds that -00:00 can mark a time known in UTC with an unknown local offset ³. ISO 8601-1:2019 is the current base standard for these forms ⁹.

Step 3: cite the version you read

Online legal texts change. Each official database states how current it is. legislation.gov.uk said its UK MAR Article 17 page was up to date for changes in force on or before 6 November 2026 ⁶. The Canadian Justice Laws Website said its Interpretation Act page was current to 19 October 2026 ⁵. EUR-Lex labels consolidated texts with a date, such as 4 December 2024 for one consolidation of the Market Abuse Regulation ¹⁰.

Put that date in your citation. A reader can then check whether a later change happened after you read the text.

Step 4: handle statistics with care

A statistic belongs on a timeline at its reference period, with its release date noted. The US household survey uses the calendar week that contains the 12th day of the month as its reference period, in general, and the establishment survey uses the pay period including the 12th ⁷.

First estimates can change. BLS routinely revises the prior two months of establishment survey estimates and treats an estimate as final only after two successive revisions, with a yearly benchmark adjustment ⁷. The UK Office for National Statistics defines revisions as updates that improve quality, and corrections as amendments made in response to mistakes ⁸. Record which vintage of the number you used.

A simple record layout

A plain table is enough for most work. Each row should hold the following fields.