2.3 Identifiers

Identifiers are used as names.

Syntax

identifier ::=
identifier_letter {[underline] letter_or_digit}

letter_or_digit ::= identifier_letter | digit

An identifier shall not be a reserved word.

Static Semantics

All characters of an identifier are significant, including any underline character. {case insensitive} Identifiers differing only in the use of corresponding upper and lower case letters are considered the same.

5.a

Discussion: 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).

Implementation Permissions

In a nonstandard mode, an implementation may support other upper/lower case equivalence rules for identifiers[, to accommodate local conventions].

Examples

Examples of identifiers:

Count X Get_Symbol Ethelyn Marion

Snobol_4 X1 Page_Count Store_Next_Item

Wording Changes from Ada 83

8.a

We no longer include reserved words as identifiers. This is not a language change. In Ada 83, identifier 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.

8.b

Ramification: Because syntax rules are relevant to overload resolution, it means that if it looks like a reserved word, it is not an identifier. As a side effect, implementations cannot use reserved words as implementation-defined attributes or pragma names.

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