Use a grade 1 word indicator before a longer sequence when a letters-sequence after the beginning could be read as a shortform. No other contractions may be used within the longer sequence.

This section presents the underlying rules governing the transcription of Technical Material. Some of the more common symbols are defined and simple examples of their use are included.

More detailed examples, lists of symbols and guidance covering a wider range and complexity of technical material are provided in the publication Unified English Braille, Guidelines for Technical Material.

Refer to: Guidelines for Technical Material when dealing with works of a technical nature, such as educational material in the areas of Mathematics, Science and Computer Studies.

Computer notation is any text written in a formal syntax that is designed to allow computers to utilize the text directly for technical purposes related to the computer itself. Examples include computer programs written in procedural languages such as Java, C++, COBOL, and various "assembly" languages, nonprocedural scripting and markup languages such as XHTML, and data files prepared to meet the input requirements of specific programs. 

Note: 

• "Displayed" computer notation is presented in one or more lines separate from the surrounding literary text; 

• "inline" computer notation is presented within ordinary literary text, for example, an email address mentioned within a sentence.

A displayed computer program or program fragment should normally be transcribed in grade 1 braille; nearby excerpts from a program that is displayed in grade 1 should preferably also be in grade 1, for consistency. Other expressions, such as email addresses, web sites, URLs, filenames, and computer expressions not displayed on separate lines, should normally be transcribed in grade 2 braille.

Refer to: Section 2, Terminology and General Rules, for the "Standing Alone" rule; and also to Section 10, Contractions, for examples of email and web addresses. 

Refer to: Guidelines for Technical Material, Part 17, Computer Notation, for an example of a program fragment. 

Some common operation signs

+ plus

− minus (when distinguished from hyphen)

× times (multiplication cross)

÷ divided by (horizontal line between dots)

Some common comparison signs

= equals

< less than, or opening angle bracket

> greater than, or closing angle bracket

Refer to: Guidelines for Technical Material, Part 3, Signs of Operation, Comparison and Omission, for a full list of operation and comparison signs.

When isolated calculations appear in a literary text, the print spacing should be followed.

Follow print spacing in any technical notation where spacing is significant. If unsure of its significance, follow the print spacing as long as the presence or absence of spaces is clear. In cases where print spacing is indeterminate or known not to be significant, spacing should be used to reflect the structure of the expression or equation.

Note: In most common mathematics including algebra, operation signs should be unspaced on both sides but comparison signs should be spaced.

Refer to: Guidelines for Technical Material, Part 1, General Principles, for more advice on the spacing of technical material.

A simple numeric fraction is one whose numerator and denominator contain only digits, decimal points, commas or separator spaces and whose fraction line in print is drawn between the two vertically (or nearly vertically) arranged numbers. In such a case a numeric fraction line symbol is used between the numerator and denominator and continues the numeric mode.

Mixed numbers should be treated as two unspaced numeric items.

The numeric fraction line is not used when the print is expressed linearly using an ordinary forward slash symbol. In such a case the same symbol is used as in print.