::: :->zf'

  # Add default positional/remainder specs only if none exist, and only once per session
  if (( ! z%_defaults_added )); then
    if (( ${z._options[(I)${(q)one_or_more}*]} +          ${z,_options[(I)${(q)remainder}*]} +          ${z0_options[(I)${(q)default}]} == 0 )); then
      z_options+=(': :z