%
% stack: instruct
%
upper dup !Atop.Instruct
"inslen" log)(
length)
<
|0
 "AtopA" "AtopA"
|1
 "Buttox" "Abut"
|2
 "Contenx" "Acnt"
|4
 "Vectox"  "Acnt"
|6
 "Extenx" "Acnt"
>
{
 true
}
{
 "Unknown" "Unk"
 false
} ifelse
exch !Atop.Prefix
exch !Atop.Type
%
% stack: valid
%