@Nick:

Thanks for the explanation, it's very kind of you!

@John:

You are right, this actually works. However, this will also exclude the
trees
whose property value is empty, for example, the following tree will be
excluded,
which will not be excluded if "myproperty<>nil" syntax works:

* Tree
:PROPERTIES:
:myproperty:
:END:

But there's probably no point to have such empty property after all. So you
approach is acceptable. Thanks!

Regards,

York


On Thu, Oct 13, 2016 at 11:57 AM, Nick Dokos <ndokos@gmail.com> wrote:

> York Zhao <gtdplatform@gmail.com> writes:
>
> > Thank you very much Nick.
> >
> > (info "(org) Using the mapping API") was the first doc I read which has
> very little information on how
> > to use the "match" parameter.  (info "(org) Matching tags and
> properties") does have a lot more detail
> > though.
> >
>
> Understood - I like to give more complete information for two reasons:
>
> 1) I don't know what you have seen already, so maybe I can save an
>    exchange or two on the list by being more complete - and if you
>    have seen it already, no harm done.
>
> 2) Perhaps I'm fooling myself, but I like to think that somebody down
>    the line is going to have the same question, and if gmane ever
>    comes back :-), they might be able to search the list and find the
>    information that they need without having to send an email to the
>    list (or even if they do, somebody might be around who remembers
>    and can do the search and reply with "See this message").
>
> So no disparagement/offense meant at all, that is just my modus operandi.
>
> Regards,
> --
> Nick
>
>
>