Problem: extracting elements on CAS mode

[compsystems]

ok ^

index:=0; "abc"[2]; returns "[] index start 0"
History input: "abc"(3) output "c" // ok,

but the history input must be "abc"(2) and not "abc"(3)

a pos 0
b pos 1
c pos 2

index:=1; "abc"[2]; returns
input: "abc"(2) output "b" // ok

//

calling index id content returns

index [enter] x:"Error: Bad Argument Value"

//

m1:=[[1,2],
[3,4]];

m1(3,1) returns "m" ?