Help:Using old PrimePages data

This page describes how to handle old (before ca. 1996) PrimePages data when importing it into this Wiki.

Importing dates

Several dates in the PrimePages prior to about 1996 are placeholders, where only part of the date (and none of the time) is actually known. A date can usually be identified as a placeholder if the time is "4:59:59" or "5:59:59". Most placeholders, but not all, are on the first day of the month. All/most of the old dates/times were entered in CST/CDT (U.S. Central Time Zone) as the last day, minute, and second of the month/year in which they were discovered, i.e. local time of 23:59:59. When PrimeGrid took over management of the site, all of the times were converted to UTC. This had the effect of adding 5 (if that date fell within daylight saving time under the rules of that time) or 6 hours (otherwise) to them, resulting in all these placeholder dates now being shown on the 1st of the following month.

When importing placeholder date data into the Wiki for prime submissions at the PrimePages, we follow this procedure:

• If the date is Jan. 1st, use only the prior year with no month or day, e.g. "1/1/1990" is shown here as "1989".
• If the date is the 1st of some other month, use the year and month of the previous month, e.g. "3/1/1993" is shown here as "1993-02", with no day shown.
• Otherwise, use the full date of the previous day, e.g. "9/3/1994 04:59:59" is shown here as "1994-09-02".