Towards a theory of quality in documentation

Diátaxis is an approach to quality in documentation.

“Quality” is a word in danger of losing some of its meaning; it’s something we all approve of, but rarely risk trying to describe in any rigorous way. We want quality in our documentation, but much less often specify what exactly what we mean by that.

All the same, we can generally point to examples of “high quality documentation” when asked, and can identify lapses in quality when we see them - and more than that, we often agree when we do. This suggests that we still have a useful grasp on the notion of quality.

As we pursue quality in documentation, it helps to make that grasp surer, by paying some attention to it - here, attempting to refine our grasp by positing a distinction between functional quality and deep quality.

Functional quality

We need documentation to meet standards of accuracy, completeness, consistency, usefulness, precision and so on. We can call these aspects of its functional quality. Documentation that fails to meet any one of them is failing to perform one of its key functions.

These properties of functional quality are all independent of each other. Documentation can be accurate without being complete. It can be complete, but inaccurate and inconsistent. It can be accurate, complete, consistent and also useless.

Attaining functional quality means meeting high, objectively-measurable standards in multiple independent dimensions, consistently. It requires discipline and attention to detail, and high levels of technical skill.

To make it harder for the creator of documentation, any failure to meet all of these standards is readily apparent to the user.

Deep quality

There are other characteristics, that we can call deep quality.

Functional quality is not enough, or even satisfactory on its own as an ambition. True excellence in documentation implies characteristics of quality that are not included in accuracy, completeness and so on.

Think of characteristics such as:

  • feeling good to use

  • having flow

  • fitting to human needs

  • being beautiful

  • anticipating the user

Unlike the characteristics of functional quality, they cannot be checked or measured, but they can still be clearly identified. When we encounter them, we usually (not always, because we need to be capable of it) recognise them.

They are characteristics of deep quality.

What’s the difference?

Aspects of deep quality seem to be genuinely distinct in kind from the characteristics of functional quality.

Documentation can meet all the demands of functional quality, and still fail to exhibit deep quality. There are many examples of documentation that is accurate and consistent (and even very useful) but which is also awkward and unpleasant to use.

It’s also noticeable that while characteristics of functional quality such as completeness and accuracy are independent of each other, those of deep quality are hard to disentangle. Having flow and anticipating the user are aspects of each other - they are interdependent. It’s hard to see how something could feel good to use without fitting to our needs.

Aspects of functional quality can be measured - literally, with numbers, in some cases (consider completeness). That’s clearly not possible with qualities such as having flow. Instead, such qualities can only be enquired into, interrogated. Instead of taking measurements, we must make judgements.

Functional quality is objective - it belongs to the world. Accuracy of documentation means the extent to which it conforms to the world it’s trying to describe. Deep quality can’t be ascertained by holding something up to the world. It’s subjective, which means that we can assess it only in the light of the needs of the subject of experience, the human.

And, deep quality is conditional upon functional quality. Documentation can be accurate and complete and consistent without being truly excellent - but it will never have deep quality without being accurate and complete and consistent. No user of documentation will experience it as beautiful, if it’s inaccurate, or enjoy the way it anticipates their needs if it’s inconsistent. The moment we run into such lapses the experience of documentation is tarnished.

Finally, all of the characteristics of functional quality appear to us, as documentation creators, as burdens and constraints. Each one of them represents a test or challenge we might fail. Or, even if we have met one now, we can never rest, because the next release or update means that we’ll have to check our work once again, against the thing that it’s documenting. Characteristics such as anticipating needs or flow, on the other hand, represent liberation, the work of creativity or taste. To attain functional quality in our work, we must conform to constraints; to attain deep quality we must invent.

Functional quality

Deep quality

independent characteristics

independent characteristics



measured against the world

assessed against the human

a condition of deep quality

conditional upon functional quality

aspects of constraint

aspects of liberation

How we recognise deep quality

Consider how we judge the quality of say, clothing. Clothes must have functional quality (they must keep us appropriately warm and dry, stand up to wear). These things are objectively measurable. You don’t really need to know much about clothes to assess how well they do those this. If water gets in, or the clothing falls apart - it lacks quality.

There are other characteristics of quality in clothing that can’t simply be measured objectively, and to recognise those characteristics, we need to have an understanding of clothing. The quality of materials or workmanship isn’t always immediately obvious. Being able to judge that an item of clothing hangs well, moves well or has been expertly shaped requires developing at least a basic eye for those things. And these are its characteristics of deep quality.

But: even someone who can’t recognise, or fails to understand, those characteristics - who cannot say what they are - can still recognise very well that the clothing is excellent, because they find it that it feels good to wear, because it’s such that they want to wear it. No expertise is required to realise that clothing does or doesn’t feel comfortable as you move in it, that it fits and moves with you well. Your body knows it.

And it’s the same in documentation. Perhaps you need to be a connoisseur to recognise what it is that makes some documentation excellent, but that’s not necessary to be able to realise that it is excellent. Good documentation feels good; you feel pleasure and satisfaction when you use it - it feels like it fits and moves with you.

The users of our documentation may or may not have the understanding to say why it’s good, or where its quality lapses. They might recognise only the more obvious aspects of functional quality in it, mistaking those for its deeper excellence. That doesn’t matter - it will feel good, or not, and that’s what is important.

But we, as its creators, need a clear and effective understanding of what makes documentation good. We need to develop our sense of it so that we recognise what is good about it, as well as that it is good. And we need to develop an understanding of how people will feel when they’re using it.

Producing work of deep quality depends on our ability to do this.

Diátaxis and quality

Functional quality’s obligations are met through conscientious observance of the demands of the craft of documentation. They require solid skill and knowledge of the technical domain, the ability to gather up a complete terrain into a single, coherent, consistent map of it.

Diátaxis cannot address functional quality in documentation. It is concerned only with certain aspects of deep quality, some more than others - though if all the aspects of deep quality are tangled up in each other, then it affects all of them.

Exposing lapses in functional quality

Although Diátaxis cannot address, or give us, functional quality, it can still serve it.

It works very effectively to expose lapses in functional quality. It’s often remarked that one effect of applying Diátaxis to existing documentation is that problems in it suddenly become apparent that were obscured before.

For example: the Diátaxis approach recommends that the architecture of reference documentation should reflect the architecture of the code it documents. This makes gaps in the documentation much more clearly visible.

Or, moving explanatory verbiage out of a tutorial (in accordance with Diátaxis demands) often has the effect of highlighting a section where the reader has been left to work something out for themselves.

But, as far as functional quality goes, Diátaxis principles can have only an analytical role.

Creating deep quality

In deep quality on the other hand, the Diátaxis approach can do more.

For example, it helps documentation fit user needs by describing documentation modes that are based on them; its categories exist as a response to needs.

We must pay attention to the correct organisation of these categories then, and the arrangement of its material and the relationships within them, the form and language adopted in different parts of documentation - as a way of fitting to user needs.

Or, in Diátaxis we are directly concerned with flow. In flow - whether the context is documentation or anything else - we experience a movement from one stage or state to another that seems right, unforced and in sympathy with both our concerns of the moment, and the way our minds and bodies work in general.

Diátaxis preserves flow by helping prevent the kind of disruption of rhythm that occurs when something runs across our purpose and steady progress towards it (for example when a digression into explanation interrupts a how-to guide).

And so on.

Understanding the limits

It’s important to understand that Diátaxis can never be all that is required in the pursuit of deep quality.

For example, while it can help attain beauty in documentation, at least in its overall form, it doesn’t by itself make documentation beautiful.

Diátaxis offers a set of principles - it doesn’t offer a formula. It certainly cannot offer a short-cut to success, bypassing the skills and insights of disciplines such as user experience or user interaction design, or even visual design.

Using Diátaxis does not guarantee deep quality. The characteristics of deep quality are forever being renegotiated, reinterpreted, rediscovered and reinvented. But what Diátaxis can do is lay down some conditions for the possibility of deep quality in documentation.