Conditional translation

The following listing displays the conditional translation:

%ifdef <def_name>    conditional translation 
%ifndef <def_name>   (<def_name> can be macro as well)
%if <condition> [%-comment]
%if (<boolean expression>) [%-comment]
%else 
%elif <condition> [%-comment] as a %else/%if sequence
%elif (<boolean expression>) [%-comment] as a %else/%if sequence
%endif