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The Nemeth Code


If you are looking for Nemeth braille transcribing services, please see our link information for CHPI.

If you want to become a certified Nemeth transcriber, you will need to take the official training from the Library of Congress. This site is for information only and is not intended to substitute for information approved by the Braille Authority of North America.

Table of Contents for This Page

  1. Introduction
  2. What's different about these pages?
    1. 1. Introduction and Orientation: A Framework for Looking at the Nemeth Code
    2. 2. The Nitty-Gritty of the English-letter, Numeric, and Punctuation Indicators
  3. Some introductory examples
  4. References and links
  5. Table of Contents for Nemeth Information


The Nemeth code is used for transcribing mathematics, science, and most other technical material to braille. However, the Computer Braille Code is used for computer-related information, such as email and Web addresses and actual computer programs, that require exact one-to-one transcription and the Chemistry Code, which is an extension to the Nemeth code, is used for complex chemical information that cannot be handled within the basic Nemeth code.

The rules of the Nemeth code are used to transcribe both text and mathematical portions of technical material. The most significant difference between Nemeth braille and standard literary braille (or English Braille American Edition), besides the new symbols, is the use of context-dependent rules that require shifting back and forth between

Another difference from literary braille is that the Nemeth code rules used in a literary context are not identical to those for standard literary braille although they are quite similar. The most obvious change is the use of the dropped or lower-cell numerals rather than upper-cell ones but there are numerous other changes as well.

What's different about these pages?

There are a lot of other Nemeth resources so asking what's different about these pages is a good question.

These pages are an attempt to fill two important gaps that I discovered while trying to learn Nemeth.

1. Introduction and Orientation: A Framework for Looking at the Nemeth Code

First, I felt the need for a simple framework to provide some orientation before I plunged into the details of all the examples and rules. I finally came to the idea of relating Nemeth to HTML. I also developed a method of typing the meanings of the cells directly underneath the cells when I got tired of looking at dots.

I hope that some others will find these introductory pages useful. They might be helpful for someone who knows literary braille and has been trying to decide whether to learn Nemeth, for a parent or mainstream teacher who wants to get a sense of Nemeth, for anyone looking for a starting point, and perhaps even for someone who knows Nemeth but not HTML.

I added a page about the proposed Unified English Braille Code because I was really appalled when I discovered that the UEBC would completely discard Nemeth.

2. The Nitty-Gritty of the English-letter, Numeric, and Punctuation Indicators

Second, I kept finding I was going around in circles trying to understand the English-letter, Numeric, and Punctuation Indicators. For example, on page 27 of the Nemeth Reference I had read, "The effectiveness .. of the English-letter Indicator [extends] to a 'short-form combination'" but then on page 30 the first examples show an English-letter Indicator before each of the letters in the symbol ab.

I suppose those of you who already know Nemeth are laughing and now that I've figured out my misunderstanding, the explanation seems obvious. Nonetheless, I decided that it would be very useful to try to summarize the complete rules for the three key Indicators.

This project took a lot longer and covered a lot more ground than I had anticipated so I'm posting the results in the hope that they will be of some use. There are five technical pages that contain complete summaries of the rules. These complete summaries are themselves cross-referenced to the Nemeth code book.

I've linked all the information together so you can approach it either top-down or bottom-up. The top-down alternative starts with a not too technical overview of the use of each of the three Indicators. The bottom-up alternative is a set of simple examples that are cross-linked (via hyperlinks) with the other pages.

Some introductory examples

Here are four brief examples to get you started in Nemeth. Please note that this is a complex subject and you can't necessarily generalize from these examples.

  1. This is some simple algebra.
  2. The letter x stands for the unknown.
  3. The unknown is represented by the letter x.
  4. PROBLEM 4. x + 2 = 4
Line 1. is an ordinary sentence using words, spaces, and punctuation, is literary context and will be transcribed identically in Nemeth and literary braille.

Line 2. is an ordinary sentence except for the mention of the mathematical symbol, x, which creates local mathematical context. The mathematical context is terminated by the space following the symbol. This sentence will again be transcribed using the same cells in Nemeth and literary braille. However the letter sign is called the English-Letter Indicator in Nemeth.

Line 3. is quite similar to line 2. but there is literary punctuation immediately after the mathematical symbol that requires a new symbol, the Nemeth Punctuation Indicator (dots 456), to explicitly terminate the mathematical context so the period punctuation mark isn't misread as a dropped numeral four.

Line 4. is a literary phrase with a mathematical expression following it and is transcribed as shown below.

,,PRO#M #4_4 X+2 .K #4 [ASCII braille] and
,,PRO#M #4_4 x+2 .K #4 [Simulated braille (if installed)]

Note that the Letter Indicator is not needed before the symbol x in this math context and the Numeric Indicator is only needed before the two numbers preceded by spaces in braille. Some Nemeth symbols, such as the two-cell braille equals symbol, may seem strange in ASCII braille but are easy to read in simulated braille because of their similar appearance to their print counterparts. (You can find more Nemeth examples starting with the page that compares Nemeth with HTML.)

The reader may have noted that Nemeth follows similar rules to literary braille in not necessarily indicating italics. The italics commonly used for mathematics in print are not used in braille when the "distinction is sufficiently indicated by other means" such as the English-letter Indicator or the obvious mathematical nature of the material. The Nemeth Code Book states,

When any material, mathematical or literary, is printed in non-regular type that has no mathematical significance, the variant type form must not be represented in the transcription. ... [The practice of printing formulas in italicized type] must not be carried over to the transcription unless the author has specifically distinguished between two meanings of the same letter .... Rule VI. Sec. 34.b.

References and links

There are at least two books you will eventually need to get from the American Printing House for the Blind (APH) if you want to become a Nemeth expert:

The rules for Nemeth are also online at Braille through Remote Learning.

Far and away the very best Internet source for teachers is the wealth of Nemeth information, math teaching strategies, and other valuable resources provided by Susan Osterhaus of the Texas School for the Blind and Visually Impaired (TSBVI). There is a tremendous amount of information on the pages themselves including detailed answers to questions from teachers, parents and students. There are also many downloads and links and information about a Math Packet which is available in print.

Many of the above references will be useful for persons who want to transcribe Nemeth but who don't necessarily have a mathematical background. The rules are presented by using lots of examples and avoiding unnecessary reference to mathematical concepts.

Table of Contents for Nemeth Information on this Website

1. Introduction and Orientation: A Framework for Looking at the Nemeth Code

2. The Nitty-Gritty of Indicators

Start here:

or here:

to get to more than you ever wanted to know about Nemeth Indicators:

This page was first posted February 21, 2002 and last modified October 04, 2002.

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