The GNU C Library version 2.19, released February 8, adds support for version-3 format tz binary files. I thought I'd give this list a heads-up, in case other C-library maintainers are lurking and want to keep up with the Joneses. As you may recall, version 3 is a minor extension to the binary format, which adds support for some less-common timekeeping practices. So far, the only tz-database timestamps affected by this change are time stamps after the year 2037 in America/Godthab with tz data 2013e or later. These time stamps cannot be described by a POSIX TZ string, so version 3 uses the quasi-POSIX string 'WGT3WGST,M3.5.0/-2,M10.5.0/-1'. The glibc 2.19 announcement is at <https://sourceware.org/ml/libc-alpha/2014-02/msg00224.html>. More details about this change can be found at <https://sourceware.org/bugzilla/show_bug.cgi?id=15968>.