Hold a signal: the operator answers after a short reaction time. Signals as described by CCOHS (Government of Canada). Charts differ for STOP and EMERGENCY STOP: agree on the signals with the operator before the lift. One designated signaller at a time, but anyone may give STOP (Alberta OHS Code s.71, s.191; Ontario O. Reg. 213/91 s.104, s.106). CSA Z150 (mobile cranes) is the national standard.
Hook block and balls are part of the load (chart notes, "weight reductions for load handling devices"). The 26 ft extension stowed: this guide lists no reduction; some charts do, so read your chart's notes.
Rows: radius (ft). Columns: main boom length (ft). (Angle) = loaded boom angle. Shaded = above the bold line: structural strength governs. * = based on maximum boom angle. Radius not listed: use the next longer radius. Boom length between columns: use the lower rating. Source: Grove RT540E product guide, chart A6-829-104278 (100 %), #4001 (50 %), #8001 (0 %), as published by Bigge and Maxim Crane; the guide says it is not for operating the crane.