fdrop
( r – ) floating “f-drop”
fnip
( r1 r2 – r2 ) gforth-0.2 “f-nip”
fdup
( r – r r ) floating “f-dupe”
fover
( r1 r2 – r1 r2 r1 ) floating “f-over”
fthird
( r1 r2 r3 – r1 r2 r3 r1 ) gforth-1.0 “fthird”
ffourth
( r1 r2 r3 r4 – r1 r2 r3 r4 r1 ) gforth-1.0 “ffourth”
fswap
( r1 r2 – r2 r1 ) floating “f-swap”
frot
( r1 r2 r3 – r2 r3 r1 ) floating “f-rote”
f-rot
( r1 r2 r3 – r3 r1 r2 ) floating “f-not-rote”
ftuck
( r1 r2 – r2 r1 r2 ) gforth-0.2 “f-tuck”
fpick
( f:... u – f:... r ) gforth-0.4 “fpick”
Actually the stack effect is r0 ... ru u -- r0 ... ru r0
.