SC on Reflow to Single Column

SC Shortname

Reflow to Single Column
SC Text

Content can be displayed as a single column.
Suggested Priority Level

Level A
Proposed:

A mechanism is available to reflow the visible content to a single column
presentation that arranges the text in a proper reading order of the
document. Tabular data may appear as multi-column tables, so long as lines
of text within table cells fit within the line length selected by the user.
If no user agent for a given content type has a mechanism for the reflow
described here, then an alternative data type must be provided that does
support this criterion.
Related Glossary additions or changes

Tabular Data
    a two-dimensional array of data points for which inclusion of a data
point within a row and column conveys meaning about the data point that
cannot be derived from the data point alone. Data points may be complex
objects like list, paragraphs or even nested sets of tabular data.
Partial Reading Order
    Let S = {e1,...eN} be the set of visible elements in a document. We say
eI precedes eJ in the partial reading order, whenever eI must logically
precede eJ in every reading of the document.
A Proper Reading Order
    Any linear arrangement, A =(f1,...,fN), of the set of visible elements
in a document is a proper reading order whenever fI precedes fJ in the
partial reading order implies fI comes before fJ in the arrangement, A.
Intuitively, if we read the visible elements in the order given by A, the
document will make sense.

What Principle and Guideline the SC falls within.

Principle 1, Guideline 1.4 and Principle 1, Guideline 1.3, Flexible Data.
Guideline 1.3.2 Meaningful Sequence
Description

Simply Put: Every web page can be put into one column in a reading order of
the document. Multi-column data tables can be left as such.
Benefits

    For many people, with and without disabilities, it is more difficult to
read when they have to scroll from the bottom of a column of text to the
top of another column. For some people with low vision, with multiple
columns, they have to scroll up several screens to get from the bottom of
one column to the top of the next. Additionally, the scrollbar and cursor
is harder to find for some. Getting from the bottom of a column and finding
the top of the next column can take considerable attention. This degrades
reading flow and comprehension, sometimes significantly.
    The Scanning Problem: Searching for a specific item within a page of
information is difficult for almost everyone with low vision. The ability
to only scroll in one direction vertical or horizontal but not both,
dramatically simplifies this problem. (TSBVI,Specific Eye Conditions,
Corresponding Impact on Vision, And Related Educational Considerations)
    Two column or more do not support large print text. Even if text stay
within column boundaries, multi-column format will not provide enough space
for text in large print. Medium length words will not fit. The excessive
hyphenation becomes distracting.
    Single column elements word-wrap easily. For HTML can be done easily
with CSS. It is harder to resize intelligently when elements are scattered
all over the page. This criterion is in fact a necessary condition for a
reasonable useful text resize criterion.

User Need: Users can set blocks of text in one continuous block, instead of
in multiple columns.

Source: Accessibility Requirements for People with Low Vision, Section 3.2.2
Testability

Test 1: (Necessary Conditin) Read and entire document with a screen reader
using its native "read all" command. If the reading does not trace a proper
reading order, then the document fails.

Validity of Test 1: The screen reader will read the document in an order
that is determined by the content. If that is not a proper reading order
then the content does not contain enough deterministic information to read
correctly. Linear reading order is not accessibility supported.

Test 2. Use the "Basic Structure Check" from the "Easy Checks - A First
Review of Web Accessibility". If the visible elements on the page
constitute a proper reading order then the page passes.

See Tests for SC 1.3.2
Techniques
Existing Relevant Techniques

    G57: Ordering the content in a meaningful sequence (Note: Proper
Reading Order and meaningful sequence are the same in this context.)
    C6: Positioning content based on structural markup
    C27: Making the DOM order match the visual order
    FLASH15: Using the tabIndex property to specify a logical reading order
and a logical tab order in Flash (Flash)
    PDF3: Ensuring correct tab and reading order in PDF documents
    SL34: Using the Silverlight Default Tab Sequence and Altering Tab
Sequences With Properties (Silverlight)

New Techniques
Write content in a way that the source order of elements is a proper
reading order.