bit (boolean)
 simpler
 constructor
  no, yes (nay, yea; false, true)
 control flow command
  xcond, cond, if statement, if expression (ternary if)
natural
 simpler of arbitrary size
 constructor
  zero, successor(natural)
 basic control flow command
  primitive repetition (times, nat_iter)
 destructor
  predecessor(natural)
 conversion to bit
  positive
 derivative control flow command
  primitive repetition (times binding, primrec, pascal's for, fold)
version number
 simpler with arbitrary number of predecessors
 constructor
  initial, version_successor(version,natural)
 destructor
  version_predecessor(version,natural,natural)
 conversion to natural
  most_significative_component (leftmost_component)
 control flow command
  lexicographic-recursion, recursion + heuristic termination proof, nat_iter + higher-order functions + heuristic termination proof