What does `rtc` field stand for on quotes?

[brandonros]

{
    "ask": 375.45,
    "beta_1_year": 1.0076145,
    "bid": 375.41,
    "ch": -6.7,
    "chp": -1.74,
    "country_code": "US",
    "currency_code": "USD",
    "current_session": "post_market",
    "description": "SPDR S&P 500 ETF TRUST",
    "dividends_yield": 1.6079565,
    "exchange": "Cboe BZX",
    "fractional": false,
    "high_price": 389.31,
    "industry": "Investment Trusts/Mutual Funds",
    "is_tradable": true,
    "language": "en",
    "local_description": "SPDR S&P 500 ETF TRUST",
    "logoid": "spdr-sandp500-etf-tr",
    "low_price": 377.38,
    "lp": 377.39,
    "lp_time": 1663804335,
    "minmov": 1,
    "minmove2": 0,
    "open_price": 386.11,
    "original_name": "BATS:SPY",
    "prev_close_price": 384.09,
    "pricescale": 100,
    "pro_name": "AMEX:SPY",
    "provider_id": "ice",
    "rch": -1.87,
    "rchp": -0.5,
    "rtc": 375.52,
    "rtc_time": 1663801141,
    "sector": "Miscellaneous",
    "short_name": "SPY",
    "timezone": "America/New_York",
    "type": "fund",
    "update_mode": "streaming",
    "volume": 106708008
}

example. it is like lp (last price) stops updating after market session, and you need to switch to looking at rtc for pre_market / post_market sessions