Good day, I write here to you knowledgeable people in the hopes you can clarify some things regarding the format of leap-seconds.list file. Please forgive me if there is a more appropriate place to ask. Recently it seems the IERS has changed the format of the leap-seconds.list file they serve[1], from the old format by NIST[2]. The comments are reworded, the lines wrap at a large width, and most importantly, the whitespace between the decimal timestamps and time-differences, previously a tab, have been replaced with spaces. [1] https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list [2] ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list This, coupled with the fact that the tz repository recently began fetching from this source (I understand that is because the NIST source was flaky), has broken a leap-seconds.list parser[3] used by the standard library of the Hare systems programming language[4], a language akin to a modern C. I'm the maintainer of the Hare stdlib date/time subsystem[5]. [3] https://git.sr.ht/~sircmpwn/hare/tree/d0c057dbbb0f1ee9179769e187c0fbd3b00327... [4] https://harelang.org/ [5] https://harelang.org/who For context, Hare sources leap-seconds.list for UTC-TAI leapsecond data and implements timescales like UTC, TAI, GPS, etc. Hare could source from a TZIF file specified by $TZ, but the decoupling of timezone and leapsecond data allows for multi-timescale programming. We are working to improve Hare and to begin stable quarterly releases, so we ideally want guarantees for how leap-seconds.list is formatted. My questions are: * What was the motivation for the changes in IERS'es leap-seconds.list file? Is there a record of discussion regarding this? * What was the motivation specifically for the spaces-to-tab change? Did another commonly used software implement a forgiving parser? * What is the history of the leap-seconds.list file and file format? * Is the format for leap-seconds.list defined? Where and how strongly? * If there is no strong, formal definition, would a formal definition of the leap-seconds.list file format be welcome? To whom could I coordinate with? * Could at least the spaces be changed back to tabs? Personally, I do not like the idea of a make-time conversion script. It would be ideal for the source file to make this change, but before I email the contact mentioned in the new file, I thought to prod here first. Timely regards, b