[pmwiki-users] Categories (and nested categories) in Action

John Rankin john.rankin at affinity.co.nz
Mon May 4 18:50:19 CDT 2009

>Date: Mon, 4 May 2009 08:45:05 -0800
>From: Chris Lott <chris at chrislott.org>
>Subject: [pmwiki-users] Categories (and nested categories) in Action
>Can anyone point me to examples in "the wild" of categories and,
>particularly nested categories, in action? I'm trying to get my mind
>around how they might work in a real implementation...

I am bending my head around the same question at the moment, in
the context of using category markup to generate a book index
from the PublishPDF recipe. Nested categories are particularly
relevant, as in an index one often wishes to have entries like:

Italics, see Markup, emphasis

    emphasis, ii
    strong, jj
    typewriter, kk

and so on. The physical form of a book index helped me to 
understand the semantics of categories and how to use them.

After much experimentation, I found the following scheme worked
for nested categories (YMMV):

[[!(Markup) emphasis]] interprets "emphasis" as a sub-category
of [[!Markup]]. This structure allows the same term to appear
in 2 or more different parent categories, e.g.

[[!(Planet) Mercury]]

[[!(Element) Mercury]]

On page Category.ElementMercury one may wish to add [[!Element]]
markup, to make the relationship explicit. 

Order is not important: [[!Recovery of (Kakapo)]] produces
"Kakapo, Recovery of" in the index.

So the title chosen for the post contains one answer to 
the question!

If one needs 3 levels (e.g. Element - Metal - Mercury), it is
harder to know what's best. So far, I don't have a solution I'm
comfortable with.

I'm stil working on this, so don't have a live example as yet. 
But if it helps, I'm happy to give more examples.
John Rankin
Affinity Limited
T 64 4 495 3737
F 64 4 473 7991
john.rankin at affinity.co.nz

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