Lesson 6.7: Plus, Minus, and Negation
There are indicators in UEB that apply to the item appearing just before or after the indicator. An item is defined as any one of the following groupings if they appear in the position affected by the indicator:
- An entire number, i.e. the initiating numeric symbol and all succeeding symbols within the numeric mode thus established (which would include any interior decimal points, commas, separator spaces, or simple numeric fraction lines).
- An entire general fraction, enclosed in fraction indicators.
- An entire radical expression, enclosed in radical indicators.
- An arrow.
- An arbitrary shape.
- Any expression enclosed in matching pairs of round parentheses, square brackets or curly braces.
- Any expression enclosed in the braille grouping indicators.
- If none of the foregoing apply, the item is simply the next individual symbol.
The plus-minus symbol is commonly used in mathematical expressions and equations to quantify the margin of error of a computation or measurement. It is also used to indicate that the number to the right of the symbol is really two numbers: a positive number and a negative number. The plus-minus symbol is formed with two cells, dots four five six in the first cell and dots two three five in the second cell.
The minus-plus symbol is dots four five six, dots three six. It is sometimes used in conjunction with the plus-minus sign to show that a negative value is to be taken where the positive value is indicated by the plus-minus sign.
Signs of comparison can be negated, representing the concept "not." In print, the negation is represented by the use of a vertical line or diagonal slash across the sign of comparison. In braille, this is represented by placing the line through previous item indicator immediately after the sign of comparison. The line through previous item indicator is formed with two cells, dot four in the first cell and dots one five six in the second cell.
When a question mark appears directly above the equal sign in print, its meaning is to question whether the amounts on either side of the equal sign are indeed identical. The vertical juxtaposition sign, a composite symbol indicator, is used to indicate that two symbols are combined vertically in braille. The vertical juxtaposition sign is dots one two four five six and is written unspaced between the two symbols. The upper symbol is written first, followed by the vertical juxtaposition indicator, and then the lower symbol. The vertical juxtaposition indicator must appear in grade 1 mode, as it also has a grade 2 meaning.