Enum

TradingHours

Option trading session in which the trade executed. Times are US Eastern Time. Equity and ETF options trade RTH from 09:30 to 16:00. ETF options with an extended close trade RTH until 16:15. Classes the exchange designates for extended sessions also trade GTH from 07:30 to 09:25, and Curb from 16:00 to 16:15 when their RTH ends at 16:00. Most index options trade RTH from 09:30 to 16:15. Index classes designated for extended sessions, such as SPX, VIX and XSP, also trade GTH from 20:15 on the previous evening to 09:25 and Curb from 16:15 to 17:00. On early close days RTH ends at 13:00 (13:15 with the extended close) and there is no Curb session. On exchange holidays the designated index classes trade GTH only, until 11:30.

values4 used byOptionTrade
Values
UNSPECIFIED 0
Trade falls outside a known session.
GTH 1
Global Trading Hours: the session before the regular open. It runs overnight for index options.
RTH 2
Regular Trading Hours: the main daytime session.
CURB 3
Curb: a short post-RTH session.