CST can refer to different regions. Abbreviations do not identify one global rule set. IANA identifiers such as Asia/Shanghai and America/Chicago make the intended location explicit.
Search the selector by a city name contained in the identifier. Select the location whose civil time your participant follows. A nearby city in another jurisdiction may observe different rules.
Europe/Istanbul is UTC+03:00 in the current rules. Europe/Berlin changes between winter and summer offsets. The difference depends on the date. Do not store today’s difference as a permanent rule.
The UTC instant is the shared reference for every card. Local dates can differ even when the instant is identical. Check the date as well as the displayed hour.
This tool supports 1970–2100. Historic rules and future policy changes require care; confirm unusually old dates or critical future commitments with an authoritative local source.