When this document is not sufficiently detailed, refer to <filename>/usr/ports/Mk/bsd.port.mk</filename>, which is included by all port <filename>Makefile</filename>s. Even those not hacking <filename>Makefile</filename>s daily can gain much knowledge from it. Additionally, specific questions can be sent to the <link xlink:href="http://lists.FreeBSD.org/mailman/listinfo/freebsd-ports">FreeBSD ports mailing list</link>.