diff options
Diffstat (limited to 'zic.8')
| -rw-r--r-- | zic.8 | 42 |
1 files changed, 24 insertions, 18 deletions
@@ -171,7 +171,7 @@ boundaries, particularly if causes a TZif file to contain explicit entries for .RI pre- hi transitions rather than concisely representing them -with an extended POSIX.1-2017 TZ string. +with a proleptic TZ string. Also see the .B "\*-b slim" option for another way to shrink output size. @@ -181,10 +181,10 @@ Generate redundant trailing explicit transitions for timestamps that occur less than .I hi seconds since the Epoch, even though the transitions could be -more concisely represented via the extended POSIX.1-2017 TZ string. +more concisely represented via the proleptic TZ string. This option does not affect the represented timestamps. Although it accommodates nonstandard TZif readers -that ignore the extended POSIX.1-2017 TZ string, +that ignore the proleptic TZ string, it increases the size of the altered output files. .TP .BI "\*-t " file @@ -245,10 +245,10 @@ for .PP The output file does not contain all the information about the long-term future of a timezone, because the future cannot be summarized as -an extended POSIX.1-2017 TZ string. For example, as of 2023 this problem +a proleptic TZ string. For example, as of 2023 this problem occurs for Morocco's daylight-saving rules, as these rules are based on predictions for when Ramadan will be observed, something that -an extended POSIX.1-2017 TZ string cannot represent. +a proleptic TZ string cannot represent. .PP The output contains data that may not be handled properly by client code designed for older @@ -558,12 +558,14 @@ begin the field with a minus sign if time must be subtracted from UT. .TP .B RULES The name of the rules that apply in the timezone or, -alternatively, a field in the same format as a rule-line SAVE column, +alternatively, a field in the same format as a rule-line +.B SAVE +field, giving the amount of time to be added to local standard time and whether the resulting time is standard or daylight saving. -If this field is +Standard time applies if this field is .B \*- -then standard time always applies. +or for timestamps occurring before any rule takes effect. When an amount of time is given, only the sum of standard time and this amount matters. .TP @@ -571,9 +573,13 @@ this amount matters. The format for time zone abbreviations. The pair of characters .B %s -is used to show where the -.q "variable part" -of the time zone abbreviation goes. +shows where to put the time zone abbreviation's variable part, +which is taken from the +.B LETTER/S +field of the corresponding rule; +any timestamps that precede the earliest rule use the +.B LETTER/S +of the earliest standard-time rule (which in this case must exist). Alternatively, a format can use the pair of characters .B %z to stand for the UT offset in the form @@ -663,7 +669,7 @@ Rule US 1967 1973 - Apr lastSun 2:00 1:00 D .ta \w'# Zone\0\0'u +\w'America/Menominee\0\0'u +\w'STDOFF\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u # Zone NAME STDOFF RULES FORMAT [UNTIL] Zone America/Menominee \*-5:00 \*- EST 1973 Apr 29 2:00 - \*-6:00 US C%sT + \*-6:00 US C%sT .sp .in .fi @@ -767,16 +773,16 @@ or if the leap second time given by the other fields should be interpreted as local (wall clock) time. .PP -Rolling leap seconds were implemented back when it was not -clear whether common practice was rolling or stationary, -with concerns that one would see +Rolling leap seconds would let one see Times Square ball drops where there'd be a .q "3... 2... 1... leap... Happy New Year" countdown, placing the leap second at midnight New York time rather than midnight UTC. -However, this countdown style does not seem to have caught on, -which means rolling leap seconds are not used in practice; -also, they are not supported if the +Although stationary leap seconds are the common practice, +rolling leap seconds can be useful in specialized applications +like SMPTE timecodes that may prefer to put leap second +discontinuities at the end of a local broadcast day. +However, rolling leap seconds are not supported if the .B \*-r option is used. .PP |