Algol 68 - ACM Digital Library

110 van Wijngaarden, et al.ALGOL 68 Revised ReportIll• let S be the intrinsic value of the NUMERAL of its stagnant-part:• let E be the intrinsic value of the constituent fixed-point-numeral of itsexponent-part;Case A: The constituent plusminus-option of N contains a minus-symbol:• V is the product in the sense of numerical analysis of S and 1/10raised to the power E;Case B: The direct descendent of that plusminus-option contains a plussymbolor is empty:• Y is the product in the sense of numerical analysis of S and 10raised to the power E.8.1.3. Boolean denotations8.1.3.1. Syntaxa) boolean denotation{8Oa} : true{94b} symbol ; false{94b} symbol.{Examples:a) true • false }8.1.3.2. SemanticsThe yield of a boolean-denotation is true (false) if its direct descendentis a true-symbol (false-symbol).8.1.4. Character denotations{Character-denotations consist of a string-item between two quotesymbols,e.g., "a". To indicate a quote, a quote-image-symbol (representedby .... ) is used, e.g., ' ....... . Since the syntax nowhere allows character- orstring-denotations to follow one another, this causes no ambiguity.}8.1.4.1. Syntaxa) character denotation{80a} ..quote{94b} symbol, string item{b}, quote symbol{94b}.b) string item{a,83b} : character glyph{e} ; quote image symbol{94b} ;other string item{d}.c) character glyph{b,92c} : LETTER symbol{94a} ;DIGIT symbol{94b} ; point symbol{94b} ; open symbol{94f} ;close symbol{94f} ; comma symbol{94b} ; space symbol{94b} ;plus symbol{94c} ; minus symbol{94c}.d) A production rule may be added for the notion 'other string item'{b, for which no tiyper-rule is given in this Report} each of whosealternatives is a symbol {l.l.3.1.f} which is different from anyterminal production of 'character glyph" {c} and which is not'quote symbol'.{Examples:a) "a" b) a • .... • ?C) aolO.o(o)o,o o+o-}8.1.4.2. Semanticsa) The yield of a character-denotation is the intrinsic value of thesymbol descended from its string-item.b) The intrinsic value of each distinct symbol descended from a stringitemis a unique character. {Characters have no inherent meaning, except ,insofar as some of them are interpreted in particular ways by the transputdeclarations (10.3). The character-glyphs, which include all the charactersneeded for transput, form a minimum set which all implementations(2.2.2.c) are expected to provide.}8.1.5. Void denotation{A void-denotation may be used to assign a void value to a UNITEDvariable,e.g., union ([ }real, void) u := empty.}8.1.5.1. Syntaxa) void denotation{80a} : empty{94b} symbol.[Example:a) empty }8.1.5.2. SemanticsThe yield of a void-denotation is empty.8.2. Bits denotations8.2.1. SyntaxA) RADIX :: radix two ; radix four ; radix eight ; radix sixteen.a) structured with row of boolean fieldI,ENGTH LENGTHETY letter aleph mode denotation{a,80a} :long{94d} symbol, structured with row of boolean fieldI,ENGTHETY letter aleph mode denotation {a,c}.b) structured with row of boolean fieldSHORTH Stl()RTHETY letter aleph mode denotation{b,80a} :short{94d} symbol, structured with row of boolean fieldSHORTllE'I'~ letter aleph mode denotation{b,c}.c) structured with row of boolean fieldletter aleph mode denotation{a,b,80a} :RAI)lX{d,e,f,g}, letter r symbol{94a}, RAI)IX digit{h,i,j,k} sequence.d) radix two{c,A347b} : digit two{94b} symbol.e) radix four{c,A347b} : digit four{94b} symbol.f) radix eight{c,A347b} : digit eight{94b} symbol.g) radix sixteen{c,A347b} : digit one symbol{94b}, digit six symbol{94b}.h) radix two digit{e,i} : digit zero symbol{94b} ; digit one symbol{94b}.i) radix four digit{c,j} : radix two digit{h} ; digit two symbol{94b} ;digit three symbol{94b}.