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Overview of the Major Indicators Used in the Nemeth Code
In order to learn the Nemeth code, it is necessary to have a
thorough understanding of three indicators: the English-Letter,
Numeric, and Punctuation Indicators. I found the rules for these
Indicators difficult to master until I saw how they each contribute
to efficient reading.
There are several starting points for the information presented
here about these Indicators. This page presents a non-technical
overview. A separate page has simple examples with links to five more pages that
contain complete summaries of the rules. The
summaries are linked back to the examples and also cross-referenced
to the Nemeth code book.
- The English-letter
Indicator (ELI or LI) is (dots 56) and is represented in ASCII braille by the ASCII
code for the semi-colon. The ELI has three functions in Nemeth:
- to distinguish certain letter sequences as abbreviations
- as part of the symbol when a letter from our Roman (Basic Latin) alphabet is
set in special type
- when necessary to show that one or more letters are meant as a
mathematical symbol rather than as a contracted braille word
(Click for a complete summary of the
rules for the use of the ELI.)
- The Numeric Indicator (NI) is (dots
3456) and is represented in ASCII braille by the hash mark. The NI
has two functions in Nemeth:
- as part of the symbol when an Arabic numeral is set in special
type
- as necessary to indicate when the lower-cell signs are intended
as numerals rather than as punctuation marks or other symbols
Click for a complete summary of the
rules for the use of the NI.)
- The Punctuation
Indicator (PI) is (dots 456) and is represented in ASCII
braille by the underscore. The PI complements the NI and is
sometimes needed to indicate when certain lower-cell signs are intended as
punctuation marks rather than as Nemeth numerals. Click for a complete
summary of the rules for the use of the
PI.)
Persons familiar with literary braille have probably noticed the
similarity between the letter sign and the English-letter Indicator
and also between the number sign and the Numeric Indicator. The
rules for these two indicators in Nemeth are somewhat different and
more complex than the corresponding literary braille rules. The
Punctuation Indicator is new to Nemeth.
The useage rules can be better understood and remembered by
considering the following keys:
- Nemeth is used to transcribe both text and mathematical
expressions; Nemeth was designed to avoid unnecessary changes to
literary braille.
- The readability of braille is improved by eliminating
unnecessary and redundant symbols. This is one reason why simply
using the appropriate Indicator before a symbol in all situations
is not the optimal strategy.
- Complex mathematical expressions are easier to read and easier
to manipulate without embedded indicators so Nemeth was designed to
reduce the need for embedded indicators. (Dr. Nemeth calls this
"The Continuous Notation Principle.")
- The NI and PI are complementary indicators. An NI will often be
used with a cell meant as a numeral in situations where the same
cell would not require a PI were it used as a punctuation mark and
vice versa.
- The LI does not have a complement so there is no alternative to
using the LI in contexts where a word might be possible.
The English-letter Indicator has three different functions, the
Numeric Indicator has two different functions, and the Punctuation
Indicator has only one function. The detailed information about
these Indicators that is presented here takes the unique approach
of using a different local name for an Indicator to go along with
its different functions.
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This page was first posted on February 18, 2002 and last
modified on March 05, 2002.
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