Lesson 4.0: Grade 1 Mode
A braille symbol may have a grade 1 meaning and it may also have a contracted (grade 2) meaning. Some symbols also have a numeric meaning. Grade 1 indicators are used to set grade 1 mode to identify the subsequent symbol(s) with a grade 1 meaning. There are grade 1 indicators for a symbol, a word, or a passage (three or more words or symbol sequences).
The grade 1 word indicator is formed with two cells; dots five six in the first cell and dots five six in the second cell. The grade 1 word indicator sets grade 1 mode for the next word or symbol sequence. A symbol sequence in UEB is defined as an unbroken string of braille signs, whether alphabetic or non-alphabetic, preceded and followed by a space. The grade 1 passage indicator is three cells; dots five six, five six, five six and it sets grade 1 mode for the next passage (three or more symbol sequences). The grade 1 terminator is placed at the end of the passage to turn off grade 1 mode.
The numeric indicator also turns on grade 1 mode. When grade 1 mode is set by the numeric indicator, grade 1 indicators are not used unless a single lower-case letter a-j immediately follows a digit. Grade 1 mode when set by the numeric indicator is terminated by a space, hyphen, dash, or a grade 1 indicator.
Grade 1 word and passage indicators are used to set an entire mathematical expression in grade 1 mode. The use of grade 1 word and passage indicators is often preferred over the use of multiple grade 1 symbol indicators within an expression. Placing the entire symbol sequence or passage in grade 1 mode is less intrusive than using multiple indicators within the expression, and maintains mathematical clarity for the reader.
Expressions requiring grade 1 word or passage indicators will be introduced in the next lesson.