The keys are hierarchically ordered, two levels deep. You always get back 
from the second level to the first with the q(uit) key.


                |---  i(n)
                |---  o(out)
Z(oom) ---------|---  p(an)
                |---  a(ll)
                |---  q(uit



                |---  p(oint)
                |---  l(ine)
I (Digitize) ---|---  a(rea)
                |---  a(utolabel all following items)
                |---  q(uit


                
                |---  p (remove point)
                |---  l (remove line)
                |---  a (remove area)
                |---  P (move point)
                |---  L (move line)
E(dit-----------|---  A (move area)
                |---  s(nap line to node)
                |---  b(reak line)
                |---  d(isplay nodes)
                |---  R(emove BLOCK of lines)
                |---  v (Smooth polyline)
                |---  q(uit)



                |---  p (Label points)
                |---  l (Label lines)
                |---  a (Label areas)
                |---  m (Label multiple lines)
                |---  A (Unlabel areas)
                |---  L (Unlabel lines)
L(abel)---------|---  P (Unlabel points
                |---  M (Unlabel multiple lines)
                |---  B(ulk label remaining lines)
                |---  h(ighlight lines of category #)
                |---  d(isplay areas of category #)
                |---  c (Label contours)
                |---  i (Contour interval)
                |---  q(uit)



                |---  a(rea labels)
                |---  l(ine labels)
                |---  p(oint labels)
                |---  m (area markers)
                |---  A(reas)
                |---  L(ines)
D(isplay) ------|---  P(oints)
                |---  n(odes)
                |---  o (points in lines)
                |---  s (scale)
                |---  w(here am I)
                |---  r(eset defaults)
                |---  q(uit)



                |---  u(nlabeled areas)
                |---  o(pen area lines)
E(rrors)--------|---  d(uplicate lines)
                |---  n(ode lines)
                |---  i(slands)
                |---  q(uit)



                |---  a(reas)   default: gray
                |---  l(ines)   default: blue
                |---  p(oints) default: green
                |---  A (labeled areas) default: orange
                |---  L (labeled lines)   default: magenta
                |---  P (labeled points) default: aqua
C(olor) --------|---  1 (nodes with 1 line) default: green
                |---  2 (nodes with  2 or more lines) default: red
                |---  h(ighlight) default: yellow
                |---  b(ackground) default: black
                |---  o(verlay map) default: white
                |---  r(eset defaults)



                |---  d(igitizing threshold)
                |---  s(napping threshold)
                |---  F (toggle flexible grey scale)
                |---  b(eep toggle)
                |---  a(uto window toggle)
U (Customize)---|---  O(verlay vector map)
                |---  B(ackdrop raster  map)
                |---  m (toggle auto-smoothing)
                |---  q(uit)