- See Function Argument.
- The ASCII Code
- The ASCII Code or American Standard Code for Information Interchange is a ~40-year old numerical code for the standard keyboard characters. Of course, you need some sort of key or "cheatsheet" to know which numerical code stands for which character.
- The original and still standard ASCII code has 128 different entries. (There is an extended ASCII code with 256 entries but there are various associations between codes and characters for the second half of the set.) Since 128 different numbers only require seven bits of an eight-bit computer word, this left one other bit to carry additional information on old computers. Seven-bit ASCII is the code currently used by HTML when transmitting over the Web.
You can find the key to the numerical code in many sources; it is sometimes included as an Appendix in a User's Guide to a word processor software. (This is a link to one of many keys on the Internet.) ASCII codes 65-90, for example, are the uppercase letters.
These same numbers can, of course, be used for other purposes. Braille ASCII uses the numbers 32-95 for the 63 braille cells plus the space. These are shown in the Braille ASCII chart matched, as is usually done, with the keyboard characters corresponding to the ASCII codes rather than to the numerical codes themselves.
A code key to the ASCII code—in terms of a simple display of the keyboard characters using a typewriter-like font—is typically built into even the most basic computer operating systems since it allows for text output at a very primitive level. A code key to the Braille ASCII code—in terms of the braille cells—is built into many refreshable braille displays and braille embossers; the SimBraille© font also uses Braille ASCII as its ASCII character code. (Codes 97-122 are the lower case letters in the standard ASCII code; Simbraille© and, apparently, some embossers treat these lower case codes as being equivalent to the corresponding upper case codes 65-90.) Of course, there is nothing special about the Braille ASCII code except that it is widely used. The Unicode and NUMBRL character codes for the braille cells are actually more useful because they are
The ASCII code (or an equivalent) is also used to represent characters in the source produced by a word processor. You can see this by typing in standard keyboard characters using any font with or without special font effects and changing the font to SimBraille©. (Tip! You can also change the font if you choose to display Braille ASCII and want it to be more readable.)
- Character Codes
- Character codes are the arbitrary numbers used internally by computers to represent letters and symbols. One of the earliest set of character codes is the ASCII Code; the current standard is Unicode.
- Character References
- Character references are indirect references to characters which use a name or number to refer to a character. Character references are a convenient method for indicating special characters that don't appear on a standard keyboard.
HTML has a special format for character references. An example of an HTML character reference is the name ♥ or the decimal number ♥ for the hearts suit character, ♥.
- Characters and glyphs
- A character is a abstract figure that can be identified by a name, for example, BRAILLE PATTERN DOTS-12 or a LATIN SMALL LETTER B.
- A character set is a group of characters with a common purpose such as the braille cells or the Roman alphabet. Character sets generally have names. The official Unicode name for the braille cells is Braille Patterns and that for the Roman alphabet is Basic Latin.
- A composite character is a character composed of two or more elements of a character set, such as an accented letter.
- A glyph is a particular display of a character. A glyph has an actual size and usually one of many different ways of representing the same character. A glyph can includes style, such as bold; special effects, such as color or underlining; and other features.
- A pre-composed composite character is a composite character that can be treated as a standard character but that also carries with it the necessary information to decompose it into its parts. This may be useful if the parts are identical to other characters in the character set.
- Dotless BRAILLE
- Dotless BRAILLE is the phrase used as our logo which is displayed in an interactive form of dotless braille. The second word is capitalized so it can serve as an illustration of the transcription of uppercase words in braille.
- dotless braille
- Dotless braille is any braille equivalent written without dots. The most useful forms of dotless braille are those that can be used for proofreading braille transcriptions.
- DotlessBraille is the generic name of any font that can be used to display extended braille for print readers. Cf. dotless braille and extended braille.
- dotlessbraille is the name of this website. This is spelled out with 14 characters; it does not use contracted braille. The full URL is www.dotlessbraille.org
- Enclosed List
- An enclosed list is a special construct in the Nemeth code that has the following characteristics. (References are to the 1972 Revision of the Nemeth Braille Code, Rule II--Sec. 10.) Simple examples of enclosed lists are [1, 2, 3] and (x, y) as often used in mathematics to indicate the arguments of a function. The value of this construct is that the items in an enclosed list do not require the use of the Punctuation Indicator nor of the Numeric or Letter Indicators except for items set in a special type form.
- The list is enclosed in a pair of signs of grouping as defined by Rule XVIII. The signs of grouping do not necessarily have to be be a matching pair.
- The list contains two or more items with the separator(s) being a (dot 6) mathematical comma followed by a space.
- Each item in the list is a mathematical item such as a number, symbol, or mathematical expression; words and abbreviations (except for abbreviated function names) are not allowed. The items may not include plural, possessive or ordinal endings.
- A function name, abbreviated function name, or sign of shape together with any following signs are regarded as a single item.
- An ellipsis or any sign used as a sign of omission is allowed.
- No punctuation marks other than the mathematical comma used as a separator and the ellipsis or long dash used as signs of omission are allowed.
- None of the Nemeth Code Rule XX Signs of Comparison are allowed.
- Extended Braille
- Extended Braille is a proposed replacement for the ASCII braille machine code used by transcribing applications to represent the braille characters.
- In simple terms a function is a mathematical rule that gives you an answer based on certain input data. A simple example of a rule is, "The output is two times the input." That means if the input is one, the output is two; if the input is two, the output is four, and so on. You can, of course, have more than one piece of input data.
For example, your Body Mass Index (BMI) depends on both your weight in pounds (W) and your height in inches (H) according to the formula:
BMI = 703 x W/(H x H).
Using this formula a person
weighing 210 pounds and 6 feet tall has a
BMI = 703 times 210 divided by 72 divided by 72 = 28.5.
- Function Argument(s)
- The arguments of a function are just its input. In the formula for Body Mass Index, there are two arguments, W and H. This can be written in general form as BMI = f(W, H); this form shows that the function, f has two arguments but it doesn't give you the actual formula for the function. Nonetheless, this general form is very convenient because you only have to write the formula once and then you can refer to it in a simpler and more general way.
- HyperText Markup Language is used for transmitting information on the Internet. HyperText means text that includes links that, with appropriate support from a browser, allow you to "jump" from one part of a text to another part or to an entirely different page. Markup means embedded symbols that function like printer's composition marks to control the appearance or rendering of a text. HTML allows formatted textual information to be transmitted in a linear fashion using at most 128 different ASCII characters and shares characteristics with braille.
- Keyboard Layout
- A keyboard layout determines which ASCII (or ASCII equivalent) codes are associated inside the computer with which physical keystrokes or keyboard events. The keyboard layout that is typically printed on the keys of computer keyboard is Standard 101. You can change the layout as a Setup option in most modern computer systems. Some people use the Dvorak layout because they find it easier. Other layouts are appropriate for non-Latin alphabets. Most people stick with one layout and use different mappings for different purposes.
Most keyboards can sense several keys being pressed simultaneously so that, for example, a Shift key can be used to double the number of codes. In this case, one keyboard event consists of several signals. However, if you are interested in simulated six-key typing, you've probably discovered that although most keyboards recognize up to three simultaneous keystrokes, only a few can recognize six keys being pressed simultaneously.
- Keyboard Mapping Table
- A keyboard mapping table is an internal table that determines the relationship between a keyboard event and the ultimate results. It is easiest to envision this as a two-step process. The keyboard layout determines the numerical code associated with an event and then the mapping table determines the meaning of the numerical code.
If you don't like a mapping table that is built into the software you are using, you often don't have any way of directly changing the table. A simple option is to "fool" the table by using software like KickKeys©
The way that the KickKeys© software works is that it traps a keyboard event and changes the ASCII code before it is sent to an application like a word processor that looks the code up in a font table to determine what to display.
For example, Braille ASCII uses code 052 (which is the standard ASCII code for the numeral 4 character) for the braille cell with dots 2-5-6, which represents the period punctuation mark in literary braille. The ASCII code for the period keyboard character with the standard keyboard mapping used by most American keyboards is code 046. If you use KickKeys user-friendly interface to tell it that when you are using SimBraille© you want to get dots 2-5-6 by strking the period key on a standard keyboard layout, then whenever you strike the period key while KickKeys is active, KickKeys changes the standard code 046 to a code 052 before it sends it on to the word processor. The positive aspect of this approach is that you will still get valid Braille ASCII.
Dotless Braille Tip! A keyboard mapping that has been found convenient in the past for literary braille is to use the lower-case letters for the cells that correspond to the letters while reserving some of the upper case letters for the two-letter signs such as "C" for dots 1-6 or "ch".
There are 47 keys for keyboard characters on most standard computer keyboards so, with the Shift key, there are 94 options for the 63 braille cells. KickKeys© allows you to map several different keystrokes to the same character so you could map the numerals as they are used in either literary braille or Nemeth and also map the punctuation marks properly. If you don't have any trouble remembering the letters used for numerals in literary braille, you could also use the keyboard numerals 1-7 as NUMBRL codes for the indicators with dots only in the right-hand column of a cell.
- LaTEX is a widely-used extension to the TEX formatting system that adds some new features including a more logical recognition of document structure with items such as chapters and sections. Many scientists prefer to type formulas directly in LaTEX without special software. However, there are also numerous easy to use but less efficient graphical interfaces like MathType and ScientificNotebook available for this purpose.
- Semiotics and its terms
- According to The Oxford Companion to the English Language, edited by Tom McArthur, 1992, semiotics is the study of symbols and signs. Semiotics has its own definitions for these words.
- As defined by the American philosopher Charles S. Pierce, a symbol is an arbitrary item that refers to or represents something else. A symbol can be a cartoon such as a drawing of a heart which stands for the abstract concept of love. A symbol can be the letters ell-oh-vee-ee which spell out the English word that stands for the abstract concept of love.
As used in braille terminology and especially in Nemeth, a braille symbol is a cell or sequence of cells that corresponds to an item in print. The single cell dots 1-2 is thus the braille symbol that corresponds to the print letter bee. The two cells dot 6 followed by dots 1-2 is the braille symbol for the uppercase print letter bee. The single cell dots 1-4-5-6 is the braille symbol for the two-letter print string tee-aitch.
- According to one definition, a sign is a means of communication; signs impart messages or signify. Arbitrary symbols are examples of signs but other types of signs, for example a fever indicating an illness, have a causal connection to what they refer to.
As used in braille terminology and especially in Nemeth, a print sign is what a braille symbol (q. v.) refers to. To me this terminology has the unfortunate, and, I think, incorrect implication that braille is somehow more arbitrary than print rather than simply being an alternative.
- "In semiotics, the term code refers loosely to any set of signs and their conventions of meaning."
- Source/Render Paradigm
- Source is the basic, almost abstract, information itself together with markup tags indicating how it is to be displayed under various conditions. An ideal source could be rendered in many different ways.
- Rendering is simply how information is displayed; the appearance of the information.
A browser like Netscape or Internet Explorer renders HTML and displays it on a computer screen; the Microsoft Word word processor renders text stored in its own special format for display by printing or simulated printing (Print Preview); a braille embosser renders Braille ASCII for display as embossed paper braille; a screen reader can render information as speech using speech synthesis.
The ideal is to separate the two concepts because it allows for so much more flexibility. One reason it is so easy to change the font in a document in a word processor is because the word processor stores the basic text and the formatting commands separately. The text is stored in terms of character codes or numbers (typically the ASCII code) that represent letters, numerals, punctuation marks, etc., and is unchanged by (re)formatting. (That's why the joke about the person who thought they'd save computer memory by making the size of the fonts in their documents smaller is supposed to be funny.)
- TEX is a complete computer-based formatting system used all over the world for typesetting technical material. TEX was developed by Donald E. Knuth and is documented in his The TEX Book published in 1984.
The quadratic formula, ax2 + bx + c = 0, is written as
$ax^2+bx+c=0$ in TEX. The formatting system knows all about proper typesetting for mathematics including where to put spaces. (See also LaTEX.)
- The Unicode Standard
- Unicode is a project which has essentially succeeded in the amazing goal of assigning a name and unique numerical code to every modern as well as many ancient characters as organized in character sets; Unicode also names the character sets. The latest Unicode standard names 94,140 characters!
The Unicode name for the set of braille cells is Braille Patterns. This encompasses both six-dot and eight-dot cells with the six-dot cells simply being a subset of the eight-dot set. A brief description of the code for the braille cells is included here. In the Unicode numerical order of character sets, Braille Patterns is just after Dingbats but several sets before Bopomofo, a set of phonetic symbols for learning to pronounce Mandarin Chinese.
Unicode is not involved in designing fonts or presentation of characters—although they document methods for describing characters. Their goal is to have a universal standard for naming characters to aid in information exchange.
This page was last updated September 5, 2003.