UEBC and Ambiguity
July 2002

Q. I understand that UEBC takes a very strict approach to ambiguity, so that braille is just as clear as print in representing the symbols basic to reading. But is this really necessary? Can't ambiguities such as in our current codes be resolved by considering context?

A. Yes, most of the time, even with our present ambiguous codes, you can apply common sense and figure out what the meaning "must be" because the other possible meanings do not make sense in context. But that requires that you already know something about what you are reading. What happens when you are entering into a new subject, as for example a young child might often be? Or when there is simply insufficient context present?

Q. Can you give some examples?

A. First, consider a brand name appearing in current American English Braille as


Knowledge of English words would suggest that the dots 6, 1345 is a capital N, not "ation." But is that a slash or the letter-group "st" after the first r? You can't tell unless you already happen to know the brand.

Second, if a reader of today's American math code (Nemeth code) were to encounter the braille text

.k .k #.1

he'd probably guess that the first instance of dots 46, 13 means the Greek letter kappa and the second means an equals sign (and that neither means the word "knowledge" in italics)--and he'd probably be right, provided the context is classical mathematics, since only that interpretation yields a sensible equation in normal algebraic form. In other contexts, however--e.g. if the same sequence were presented as a token list in a discussion about a computer algorithm--such assumptions would not necessarily be valid and could lead to misreading or simply confusion.

Q. Couldn't the transcriber anticipate such situations, and help the reader with an explanatory note, or grade 1 treatment, or some other device?

A. Even if we imagine that human transcribers could be expected to spot all cases of potential ambiguity and take corrective action, would we want to require such help with our basic reading? Shouldn't basic symbols be directly accessible, no matter what the context? Furthermore, more and more frequently, conversion between print and braille is being carried out by computers, with or without the added help of human transcribers. Computers thereby foster independence as well as efficiency--but they are very poor at "understanding" context or otherwise helping with ambiguity. This is true not only for conversion from print to braille, but also from braille to print.

Q. Is all this for the sake of computers, then?

A. No. Computers have no importance beyond their role as servants of people. By enabling computerized braille translation to be more accurate with less help from humans, the net effect is to make more and better braille more readily available to readers. Even transcribers benefit, being able to concentrate more on their special skills rather than routine translation issues, and thereby can produce more braille overall.

Q. Can you give me an example of where a translation error due to ambiguity might matter?

A. Let's say you braille the brand name "BrailleNote" into a note-taking device. Notice that the capital "N" has the same form as the contraction for "ation". Now, at least in the case of one such device, if you used it to translate your braille into a print document to be given to a sighted colleague, he would find himself reading "Brailleationote." Depending on the circumstances of the communication--private or public, personal or professional, for instance--it's not hard to imagine that the error might not be inconsequential in at least some of them.

Q. Couldn't that be fixed just by updating the note-taker's translation tables?

A. Of course, but that would only fix that particular instance--not the basic problem, which gives rise to an indefinite number of others like it. UEBC fixes the basic problem.

Q. How?

A. UEBC starts by making sure that it's always clear where symbols begin and end. That is, there is never any question as to whether two braille cells in sequence are to be read as a single two-cell symbol or as two separate symbols--something that is not always clear in current braille codes. That way, even if you encounter a symbol that is new to you, at least you know what to look up in a symbol table. Secondly, UEBC assigns only one meaning to any one such symbol in any one mode, a mode being a condition in effect, such as grade 1 or 2. Finally, UEBC ensures that any modes, of which there are very few, are always clearly indicated.

Q. What method is used to clarify the extent of symbols?

A. UEBC does this by providing strictly-defined "prefix-root" rules for symbol formation that both establish a firm foundation for practically all current braille symbols and also assure that additional symbols as needed, both now and in the future, can be accommodated in the same system without ambiguity.

Q. What are prefixes and roots?

A. Prefixes are cells containing only right-hand dots, plus the number sign. Roots are all other dot combinations. The basic idea is that a complete symbol is always either a root, or one or more prefixes followed by a root. (For full details, including a mathematical proof that the UEBC method is sound, see the March 1995 report of UEBC Committee II, which is available on the www.iceb.org web site.)

Q. Is this a new idea?

A. Not really; the basic concept is implicit in braille as Louis Braille originally designed it, not only in the famous "seven line" layout but also in the way that the signs were used. For that reason, virtually all current braille codes exhibit the prefix-root principle to some extent, whether consciously or not. The only thing that is new is that, in UEBC, the principle is strictly applied.

Q. Can you give some examples of how this is different from current codes?

A. In today's English codes, a dot 5 could be the beginning of a contraction or a less-than sign (in literary code and Nemeth code respectively), or a symbol in its own right (e.g. the baseline indicator in Nemeth code, or the double quote mark in computer braille code). In Nemeth code, dots 46 before dots 13 could be the beginning of a two-cell symbol for an equals sign, or the beginning of a two-cell symbol for a Greek letter kappa, or a symbol in its own right indicating that the word "knowledge" is in italics.

Q. Couldn't these ambiguities be fixed simply by changing a few symbols?

A. Possibly, if there were not many more examples, but there are--because the problem is in a fundamental aspect of code design, not only in symbol assignment.

Q. Does this mean that braille would be following print slavishly?

A. Not a chance. On the contrary, the UEBC approach makes braille fully equal to print in its ability to express the symbols fundamental to reading. A symbol, for example a "dollar sign," is after all an abstract entity that can be represented in various ways in different writing systems--print and braille are just two such systems. The UEBC philosophy is that braille can and should have the same clarity and expressive scope as any writing system. With UEBC, we can imagine that one day a blind scientist will invent a new braille symbol for some concept central to his or her new theory--and then users of print will have to come up with a corresponding print symbol, following braille!

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