tzdata rule group

Shang

Historical rule context · 1 represented zone

A rule group describes recurring clock changes. It is not itself a place or an IANA time-zone identifier.

First rule: 1919
Last rule: 1949
Rule entries: 14
Source files: asia

Notes from the time database

Context for this rule

These source notes are preserved from tzdata. They help explain a rule’s period, without adding claims beyond the source.

1919–1949

Rule context

According to this news report: on April 11, 1919, newspaper in Shanghai said clocks in Shanghai will spring forward for an hour starting from midnight of that Saturday. The report did not mention what happened in Shanghai thereafter, but it mentioned that a similar trial in Tianjin which ended at October 1st as citizens are told to recede the clock on September 30 from 12:00pm to 11:00pm. The trial at Tianjin got terminated in 1920. The Returns of Trade and Trade Reports, page 711, says "Daylight saving was given a trial during the year, and from the 12th April to the 1st October the clocks were all set one hour ahead of sun time. Though the scheme was generally esteemed a success, it was announced early in 1920 that it would not be repeated."

1948–1949

Rule context

plan

Original rule fields

Recorded rule entries

Structured directly from tzdata’s Rule lines.

From	To	Type	In	On	At	Save
1919	only	-	Apr	12	24:00	1:00
1919	only	-	Sep	30	24:00	0
1940	only	-	Jun	1	0:00	1:00
1940	only	-	Oct	12	24:00	0
1941	only	-	Mar	15	0:00	1:00
1941	only	-	Nov	1	24:00	0
1942	only	-	Jan	31	0:00	1:00
1945	only	-	Sep	1	24:00	0
1946	only	-	May	15	0:00	1:00
1946	only	-	Sep	30	24:00	0
1947	only	-	Apr	15	0:00	1:00
1947	only	-	Oct	31	24:00	0
1948	1949	-	May	1	0:00	1:00
1948	1949	-	Sep	30	24:00	0

Context for this rule

Zones using Shang

Recorded rule entries