org: Categories
10.4.1 Categories
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The category is a broad label assigned to each agenda item. By default,
the category is simply derived from the file name, but you can also
specify it with a special line in the buffer, like this(1):
#+CATEGORY: Thesis
If you would like to have a special CATEGORY for a single entry or a
(sub)tree, give the entry a ‘:CATEGORY:’ property with the special
category you want to apply as the value.
The display in the agenda buffer looks best if the category is not
longer than 10 characters.
You can set up icons for category by customizing the
‘org-agenda-category-icon-alist’ variable.
---------- Footnotes ----------
(1) For backward compatibility, the following also works: if there
are several such lines in a file, each specifies the category for the
text below it. The first category also applies to any text before the
first CATEGORY line. However, using this method is _strongly_
deprecated as it is incompatible with the outline structure of the
document. The correct method for setting multiple categories in a
buffer is using a property.