Here are the data structures with brief descriptions:

Cpf_bar_t	Single OHLCV bar pushed into the engine
Cpf_report_t	Backtest report filled by run_backtest / run_backtest_full
Cpf_security_diag_t	Per-`request.security()` site diagnostic counters
Cpf_trace_entry_t	Single per-bar trace entry
Cpf_trade_t	Closed-trade record returned in pf_report_t::trades
Cpf_version_t	Runtime version descriptor returned by pf_version_get