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<H1> 2.3 Identifiers</H1>
<DIV Class="Paranum"><FONT SIZE=-2>1</FONT></DIV>
<DIV Class="Normal"> <FONT FACE="Arial, Helvetica">Identifier</FONT>s
are used as names. </DIV>
<H4 ALIGN=CENTER>Syntax</H4>
<DIV Class="Paranum"><FONT SIZE=-2>2</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">identifier<A NAME="I1205"></A>
::= </FONT><BR>
<A NAME="I1206"></A><FONT FACE="Arial, Helvetica">identifier_letter</FONT> {[<A NAME="I1207"></A><FONT FACE="Arial, Helvetica">underline</FONT>] <A NAME="I1208"></A><FONT FACE="Arial, Helvetica">letter_or_digit</FONT>}</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>3</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">letter_or_digit<A NAME="I1209"></A>
::= </FONT><A NAME="I1210"></A><FONT FACE="Arial, Helvetica">identifier_letter</FONT> | <A NAME="I1211"></A><FONT FACE="Arial, Helvetica">digit</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>4</FONT></DIV>
<DIV Class="SyntaxIndented">An <FONT FACE="Arial, Helvetica">identifier</FONT>
shall not be a reserved word. </DIV>
<H4 ALIGN=CENTER>Static Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>5</FONT></DIV>
<DIV Class="Normal"> All characters of an <FONT FACE="Arial, Helvetica">identifier</FONT>
are significant, including any underline character. <A NAME="I1212"></A><FONT FACE="Arial, Helvetica">Identifier</FONT>s
differing only in the use of corresponding upper and lower case letters
are considered the same. </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>5.a</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1><B>Discussion: </B>Two of the
letters of ISO 8859-1 appear only as lower case, "sharp s"
and "y with diaeresis." These two letters have no corresponding
upper case letter (in particular, they are not considered equivalent
to one another). </FONT></DIV>
<H4 ALIGN=CENTER>Implementation Permissions</H4>
<DIV Class="Paranum"><FONT SIZE=-2>6</FONT></DIV>
<DIV Class="Normal"> In a nonstandard mode, an implementation may support
other upper/lower case equivalence rules for <FONT FACE="Arial, Helvetica">identifier</FONT>s[,
to accommodate local conventions]. </DIV>
<H4 ALIGN=CENTER>Examples</H4>
<DIV Class="Paranum"><FONT SIZE=-2>7</FONT></DIV>
<DIV Class="Normal" Style="margin-bottom: 0.4em"> <I>Examples of identifiers:</I>
</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>8</FONT></DIV>
<DIV Class="SyntaxIndented">Count X Get_Symbol Ethelyn Marion<BR>
<BR>
Snobol_4 X1 Page_Count Store_Next_Item</DIV>
<H4 ALIGN=CENTER>Wording Changes from Ada 83</H4>
<DIV Class="Paranum"><FONT SIZE=-2>8.a</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1>We no longer include reserved
words as <FONT FACE="Arial, Helvetica">identifier</FONT>s. This is not
a language change. In Ada 83, <FONT FACE="Arial, Helvetica">identifier</FONT>
included reserved words. However, this complicated several other rules
(for example, regarding implementation-defined attributes and pragmas,
etc.). We now explicitly allow certain reserved words for attribute designators,
to make up for the loss. </FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>8.b</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1><B>Ramification: </B>Because syntax
rules are relevant to overload resolution, it means that if it looks
like a reserved word, it is not an <FONT FACE="Arial, Helvetica">identifier</FONT>.
As a side effect, implementations cannot use reserved words as implementation-defined
attributes or pragma names. </FONT></DIV>
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