RE: Convention versus best practice versus standard

["Costello, Roger L." <costello@mitre.org>]

Hi Folks,

Really interesting discussion!  Thanks everyone for your insights!

Below is a summary. Comments welcome.  /Roger


DEFINITIONS

1. Convention - an agreement, implicit or explicit, among a group.  My
practice is mine alone, but if all or most of us do it that way (good
or bad), it's a convention, a "coming together" in agreement on this
one practice.

2. Best Practice - specifies what we *ought* to do without regard to
whether we do it.

3. Standard - what we have agreed we will in fact do, to some specified
level of detail.

EXAMPLES

1. Convention

By convention street signs in the U.S. are placed at street corners, we
expect to find them by looking up, not down, and we expect them to be
horizontal, not vertical.  The benefits of this convention are:

   - we can locate street signs quickly, 
     with a minimum of effort
   - their appearance makes it easy to 
     distinguish them from everything else

Another example: by convention books have table of contents that occur
somewhere in the first few pages, page numbers are somewhere in the
margins and they will look like a table of contents and page numbers.

And another example: by convention XML tags are indented to reveal
their nesting structure.

2. Best Practice

It is best practice, when creating XHTML documents, to wrap all
abbreviations within an <abbr> element, e.g.

   <abbr title="Extensible Markup Language">XML</abbr>

The benefit of this best practice is: people with visual disabilities
use a screen reader to read Web pages.  Screen readers often
mispronounce abbreviations.  By providing the full text version of an
abbreviation, a screen reader tool can better assist the user.

3. Standard

The XML specification is a standard. It requires, for example, every
XML document to have a root element.

Another example of a standard is the meter.

CHARACTERISTICS OF

Convention

- Oftentimes a convention is localized.  In the US the convention is to
put street signs on street corners.  In the UK the convention is to put
street signs along the road.

- Conventions evolve over time.  In the print industry the convention
of what goes into a Table of Contents, and where the TOC should appear,
have changed over time.

- Conventions oftentimes become part of the background, we don't think
about or notice them.  We only notice them when they are not followed.
For example, when an XML document is not indented we become acutely
aware of the indentation convention.

Best Practice

- A quantitative result in a qualitative direction as determined by
some metric.

Standard

- Formal adoption.

- Authority.

- Formalized agreement.

- Explicit documentation.

REDUCES COGNITIVE LOAD

Conventions and standards help reduce cognitive load.  

For example, the convention of putting the main header of a story in
big, bold font and subheaders in smaller font instantly gives the
reader some understanding of the general organization of a document.
The user doesn't have to spend the mental effort to figure out the
organization and main points.

Another example, the XML standard gives us a syntax for formatting data
- wrap data within tags.  Thus, the standard enables us to focus on the
data rather than spending the mental effort of devising a data format
syntax.