Designing a topic hierarchy

A well-designed topic hierarchy will make the reader's task of finding information in a publication easier.

Structuring the content of a document is one of the most important steps in the authoring process. It is here that you establish the logical relationship between topics, and add context to the set of topics.

Some theoretical considerations to make when deciding on the structure of topics include the following.

Translated to a document structure, this points to an ideal document structure made up of parent topics with seven child topics at every level, and no more than four generations of topic families.

A three level hierarchy with seven topics per menu will permit 343 pages. Four layers of ten topics permits up to 10,000 topics, which is more than enough for even the largest manuals.

The human mind thinks in associative, rather than linear, patterns. Thus we "get on the wrong track", and "forget how we got onto this subject". The human brain stores information in this way also, by finding a similar experience and associating it with the current experience ("this tastes like vinegar").

In DITA, concept information is separated from task and reference information. This makes it more difficult to structure a document purely around the goals of the reader, unless the nature of the information allows the creation of standard sets of one concept, one task and one reference topic. Such an information model would permit a TOC structure such as:
An alternative approach would be to group concept topics, task topics and reference topics, resulting in a high level structure such as:

In reality, however, most information models do not have such a repeatable structure. More likely is that there will be a concept topic that has three or four related task topics, with a reference topic that might be associated with a dozen concepts.

The best structure for a particular document is not something that can be easily prescribed; it is the responsibility of the author to devise a logical structure that will support the aims of the deliverable document.

You should consider the following questions when designing a TOC and a structure for your topics:

Two more specific guidelines to adopt are: