What is the proper way to maintain a local port file?

[Michael_google gmail_Gersten]

What is the proper way to maintain a local port?

There are two cases that I'm looking at:

1. Creating a new port for a program that does not currently have a port.
2. Modifying an existing port.

For 2, the specific case I'm looking at is qemu -- I only need the 386
emulator, and do not need to build the other 3 that are built by
default (and apparently have no way to turn off).

The "ideal" method as I see it, based on very limited knowledge of
what's involved, would be to edit a port file, store both the original
and my modification, and on update of the portfile trigger a "you must
inspect this portfile" warning, and show how my patches will fit into
the new portfile.

For 1, there could be any number of things that do not have a port yet
that I'd want to create and test a port for, before submitting.
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