I have added what I think the pinout is when the block is rotated.
>10-pin	DB-25	MODEM	<-JUMPER BLOCK->TERMINAL
>Header	Conn.
>1	1	Frame Ground		Frame Ground
>2	2	TXD			RxD
>3	3	RXD			TxD
>4	4	RTS			DCD
>5	5	CTS			DCD
>6	6	DSR			DTR
>7	19	SCTS (Secondary CTS)	SCTS
>8	7	Signal Ground		Signal Gnd
>9	20	DTR			DSR
>10	8	DCD			RTS+CTS

SCTS is only connected if switch SW2-7 is on. It goes
to the same ACIA input as the DCD pin (provided SW1-7
is on) so is probably best ignored unless you have
a strange device which needs it.
-- 
David Wilson  School of IT & CS, Uni of Wollongong, Australia