{% set renderBackButton = flow.getCurrentStepNumber() in (flow.getFirstStepNumber() + 1) .. flow.getLastStepNumber() %}
{#
Default button (the one trigged by pressing the enter/return key) must be defined first.
Thus, all buttons are defined in reverse order and will be reversed again via CSS.
See http://stackoverflow.com/questions/1963245/multiple-submit-buttons-specifying-default-button
#}
{% if renderBackButton %}
{# see http://www.html5rocks.com/en/tutorials/forms/html5forms/ #}
{% endif %}