IANA Time Zone vs Israel IST / IDT
IST and IDT describe the two seasonal phases of Israel's civil clock. Asia/Jerusalem is the technical identifier to use when software must determine which phase applies to a specific date. It also preserves historical transitions that a fixed UTC offset cannot represent.
Israel's National Time Standard
Israel's National Physical Laboratory maintains the national time scale under the Time Determination Law. The laboratory describes UTC(INPL) as Israel's realization of Coordinated Universal Time, maintained with high-precision atomic clocks and synchronized with international UTC. Civil Israel time is then expressed from that reference using the applicable standard or daylight offset.
UTC(INPL)The national UTC realization maintained by Israel's National Physical Laboratory.
IST civil offsetUTC(INPL) + 2 hours during standard time.
IDT civil offsetUTC(INPL) + 3 hours during daylight saving time.