What do the dates at the bottom right of the page mean? It's easy to predict a single date, but what's the difference when there are two dates?
Those are the years in which that particular publication has been copyrighted by the Jeppesen company.
$\begingroup$ Yes for sure but why are there 2 dates for some? Isn't a single date enough for their rights to be preserved? $\endgroup$– pilot162Oct 11, 2022 at 14:57
1$\begingroup$ It's the date when it was originally copyrighted, @pilot162, then when the copyright was renewed. You'll find multiple dates on many, many things like that, sometimes, 3 or 4 or 10 renewals. $\endgroup$– FreeManOct 11, 2022 at 15:10
3$\begingroup$ Copyright questions are a better fit for Law SE, $\endgroup$ Oct 11, 2022 at 15:10
$\begingroup$ @MichaelHall I am of the possibly contrarian opinion that questions belong where a person seeking an answer to that particular question is likely to look for it, even is the answer fits a different domain. That is a somewhat subjective judgement, but aviation SE seems to me to be the place for questions about the contents of Jeppesen pages. $\endgroup$– sdenhamOct 11, 2022 at 19:16
It is a requirement of copyright notices that the year of publication be included. If parts of a publication were published at different times then the year of publication for each part needs to be included in the notice.
If there is more than one date this means that parts were published on one date and part in the other - so for the first map some parts were published in 1998 and some in 2021. (I'm unclear as to whether some parts may have been published in intervening years - when I was doing this you had to include literally every year in which some part was published.)