Grade 1 mode is required to prevent a letters-sequence from being misread as a shortform or as containing a shortform.

Refer to: Section 10.9, Contractions.

A grade 1 indicator precedes a capitalisation indicator.

Use contractions in computer material, such as email addresses, web sites, URLs, and filenames when it is embedded in regular text. Use uncontracted braille for computer material, such as computer program code which is displayed on separate lines, as well as any nearby excerpts from the program.
Refer to: Section 11.10.2, Technical Material.

As words are most easily recognised when presented in their familiar contracted form, minimise the number of switches between grades, the number of indicators required and the number of cells used.

Reduce the indicators within equations. When reading mathematical expressions, passage indicators are less intrusive than interior indicators.

Refer to: Guidelines for Technical Material, Part 1.7.

Except as provided for in Rule 10.12.1, use contractions in abbreviations and acronyms, following the provisions of Section 5.7.1 and 5.7.2, Grade 1 Mode, as well as those of Section 10.1 to 10.11. 

When an expression in grade 1 mode would be equivalent to the same text in grade 2 mode because no contractions would occur, a grade 1 indicator may be used although it is not required.

Preferably, when it is known, or can be determined from the text or by reference to a standard dictionary, that letters within an abbreviation or acronym that would make up a contraction are pronounced separately as letters, do not use the contraction. In case of doubt, use the contraction.

In a work entirely in grade 1 braille (that is, using no contractions), grade 1 indicators are not used except as required for other reasons, e.g. for the lowercase letters a-j immediately following digits, and a question mark in an unusual position.

Numeric indicators set numeric mode for the remainder of the symbols-sequence.