Due to a script's unintended failure to supply a -p option to zic, I recently had my nose rubbed in the fact that localtime.c still has this as the fallback when the "posixrules" link can't be loaded: /* ** The DST rules to use if TZ has no rules and we can't load TZDEFRULES. ** We default to US rules as of 1999-08-17. ** POSIX 1003.1 section 8.1.1 says that the default DST rules are ** implementation dependent; for historical reasons, US rules are a ** common default. */ #ifndef TZDEFRULESTRING #define TZDEFRULESTRING ",M4.1.0,M10.5.0" #endif /* !defined TZDEFDST */ It's now over ten years since the US last followed those rules; isn't it time to update TZDEFRULESTRING to match current law? I can't really think of any situation where the current default would be of any value now. Apologies if this policy is being followed intentionally; but I couldn't find any discussion of the point by googling. regards, tom lane