This discussion is restricted to the use of the Numeric Indicator (NI) with Nemeth numbers and does not address numerals that are characters in a symbolic name rather than digits in a number. Rules for numbers in special contexts such as Tables and Diagrams are also not addressed.
This is a summary based on the printed Nemeth Braille Code 1972 Revision and references to numbered Rules, Sections, etc. are from the print version of that book. Some examples in the book are fragments or taken out of context. This makes it difficult when you first look at them to realize at what point the use or non-use of the NI can be determined unequivocally.
Nonetheless, in most cases of actual texts, the rules for the use and non-use of the NI depend on the requirements of the construct or mathematical template and can be determined prior to the addition of spaces or linebreaks needed only for final output on a device with a fixed line width.
Also, although it is o.k. to add NI's as needed for particular displays, it is never correct to delete NI's that are required by the rules presented here.
Since some of braille cells used for numerals are also used as punctuation marks, something has to be done to differentiate them. The Punctuation Indicator is the complement of the NI in this function.
The braille symbol for the Nemeth Numeric Indicator is the single cell dots 3456 (Rule II) which is represented in Braille ASCII by ASCII code 35 which happens to correspond to the crosshatch in the standard keyboard character representation of the ASCII code.
However, the braille symbol for the print crosshatch (also called pound sign, number sign, and hash mark) is the two cells dots 46 (Braille ASCII code 46 or keyboard period) followed by dots 3456. This same two-cell symbol is used for transcribing the print crosshatch whether it is used as a reference symbol or as a binary operator in special disciplines such as set theory. [Rule II—§9d(2) and Rule XIX]
Numbers following reference and operation symbols always require a preceding Numeric Indicator. In the case of the crosshatch (and also the asterisk), there will be two repeated cells using (dots 3456). This is correct but omission of the NI in this case is a common error.
Numbers require Numeric Indicators for two different reasons:
If the Indicator has already been used for the first reason, then the second use does not normally need to be considered. It is convenient when explaining the use of the Indicators to use different names for the different functions as follows:
An NI is never used if a TNI has already been used before the first numeric symbol of the number. As is seen from the rules for the use of a TNI, a number is only eligible for an NI if it is either an unsigned number with at least its leading numeric symbol (digit or decimal point) set in regular type or a signed negative number with at least its leading numeric symbol set in regular type. All other possible situations for unsigned and signed negative numbers will require a TNI before the leading numeric symbol so the number is not eligible for an NI.
A positive number may require a TNI but will never require an NI since the plus sign is sufficient for the purposes of the NI.
Nemeth treats the ten Arabic digits and the decimal point as numeric symbols and an NI may be required before any of these.
Where the NI is required, it is used by placing one NI immediately before and unspaced from the first digit or leading decimal point of a number whether or not there are preceding symbols or indicators that apply to the number.
#123
#.456
-#78 [Rule II—§9a(14), (15)]
+.9 [Rule XIX—§134 (1) and (2)]
Note. There is no advantage in Nemeth to the print practice of placing a leading zero before the decimal point of a decimal fraction and this is not usually done.
1. General rules
2. With the exception of an enclosed list, an NI is used before all eligible numbers preceded by any space in braille [9a] whether mathematical or literary or at the start of a new line with the exceptions of these three "pretty-printing" situations:
3. An NI is not used before a number not preceded by a space in braille (even though preceded by a space in print) aside from these specific exceptions. An NI is always required before an eligible number:
4. An NI is not used in any other situation. (In other words, the default is that an NI is not used.) Using the NI where it is not correct is just as wrong as omitting it where it is needed.
See the accompanying page on context for detailed cross-references to the Code book.
NOTE 1. The single-cell contractions "st" and "th" are not used for ordinal endings in Nemeth; these endings must be spelled out. However, the literary braille restriction on the use of the ordinal ending "d" when used in print for either "nd" or "rd" doesn't apply to its use after Nemeth numerals since there is no possibility for confusing the lower-cell numerals with the upper-cell letter "d".
NOTE 2. If a number is followed by an apostrophe-ess combination, the apostrophe must be preceded by a Punctuation Indicator. However, the ess "returns" the context to mathematical.
NOTE 3. According to the National Library Service these additional symbols have been omitted from some documentation. Also, it is a common error to forget this rule for the use of the NI, especially when the symbol incorporates the same cell as used for the NI.
Last updated February 24, 2002.