FEF
Entry-state-word  \
Exit-state-word    } Sort of a continuation
Call-state-word   /

call-state-word
30 1 Attention           Zero means simply pop frame.

27 1 Self map provided

26 1 Trap on exit

25 1 <not used>

24 1 ADI present

20 4 Destination          top two bits unused maybe.

10 10 Delta to open block

 0 10 Delta to active block

exit-state-word
22 9 <not used>

21 1 Microstack was saved on special pdl

20 1 binding block pushed Bindings remain on special pdl

0 17 Exit pc Location counter

Entry-state-word
21 10 <not used>

20 1 LCTYP                 Explict rest arg passed

17 1 Unsafe Rest arg 

16 1 Environment pointer points here

10 6 Num args supplied

0 10 Macro Local Block Origin