You can capture the results of a Rlist statement into a variable.
Declare Function Exec_Rlist
cmd = “LIST BOOKS BY @ID F1 F2 F3”
type = “OI”
dFlag = 0 ; * debug flag
rslt = Exec_Rlist(cmd,”EXECUTE”,type,dFlag)
RSLT will be a field-mark-delimited list of the output. Note that there may be some other spurious characters that you might want to strip out.