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<H1> 3.1 Declarations</H1>
<DIV Class="Paranum"><FONT SIZE=-2>1</FONT></DIV>
<DIV Class="Normal"> <A NAME="I1260"></A>The language defines several
kinds of named <I>entities</I> that are declared by declarations. <A NAME="I1261"></A>The
entity's <I>name</I> is defined by the declaration, usually by a <FONT FACE="Arial, Helvetica">defining_identifier</FONT>,
but sometimes by a <FONT FACE="Arial, Helvetica">defining_character_literal</FONT>
or <FONT FACE="Arial, Helvetica">defining_operator_symbol</FONT>.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>2</FONT></DIV>
<DIV Class="Normal"> There are several forms of declaration. A <FONT FACE="Arial, Helvetica">basic_declaration</FONT>
is a form of declaration defined as follows. </DIV>
<H4 ALIGN=CENTER>Syntax</H4>
<DIV Class="Paranum"><FONT SIZE=-2>3</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">basic_declaration<A NAME="I1262"></A>
::= </FONT><BR>
<A NAME="I1263"></A><FONT FACE="Arial, Helvetica">type_declaration</FONT> | <A NAME="I1264"></A><FONT FACE="Arial, Helvetica">subtype_declaration</FONT><BR>
| <A NAME="I1265"></A><FONT FACE="Arial, Helvetica">object_declaration</FONT> | <A NAME="I1266"></A><FONT FACE="Arial, Helvetica">number_declaration</FONT><BR>
| <A NAME="I1267"></A><FONT FACE="Arial, Helvetica">subprogram_declaration</FONT> | <A NAME="I1268"></A><FONT FACE="Arial, Helvetica">abstract_subprogram_declaration</FONT><BR>
| <A NAME="I1269"></A><FONT FACE="Arial, Helvetica">package_declaration</FONT> | <A NAME="I1270"></A><FONT FACE="Arial, Helvetica">renaming_declaration</FONT><BR>
| <A NAME="I1271"></A><FONT FACE="Arial, Helvetica">exception_declaration</FONT> | <A NAME="I1272"></A><FONT FACE="Arial, Helvetica">generic_declaration</FONT><BR>
| <A NAME="I1273"></A><FONT FACE="Arial, Helvetica">generic_instantiation</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>4</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">defining_identifier<A NAME="I1274"></A>
::= </FONT><A NAME="I1275"></A><FONT FACE="Arial, Helvetica">identifier</FONT></DIV>
<H4 ALIGN=CENTER>Static Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>5</FONT></DIV>
<DIV Class="Normal"> <A NAME="I1276"></A>A <I>declaration</I> is a
language construct that associates a name with (a view of) an entity.
<A NAME="I1277"></A><A NAME="I1278"></A>A declaration may appear explicitly
in the program text (an <I>explicit</I> declaration), or may be supposed
to occur at a given place in the text as a consequence of the semantics
of another construct (an <I>implicit</I> declaration). </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>6</FONT></DIV>
<DIV Class="Normal"> <A NAME="I1279"></A>Each of the following is defined
to be a declaration: any <FONT FACE="Arial, Helvetica">basic_declaration</FONT>;
an <FONT FACE="Arial, Helvetica">enumeration_literal_specification</FONT>;
a <FONT FACE="Arial, Helvetica">discriminant_specification</FONT>; a
<FONT FACE="Arial, Helvetica">component_declaration</FONT>; a <FONT FACE="Arial, Helvetica">loop_parameter_specification</FONT>;
a <FONT FACE="Arial, Helvetica">parameter_specification</FONT>; a <FONT FACE="Arial, Helvetica">subprogram_body</FONT>;
an <FONT FACE="Arial, Helvetica">entry_declaration</FONT>; an <FONT FACE="Arial, Helvetica">entry_index_specification</FONT>;
a <FONT FACE="Arial, Helvetica">choice_parameter_specification</FONT>;
a <FONT FACE="Arial, Helvetica">generic_formal_parameter_declaration</FONT>.
</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>7</FONT></DIV>
<DIV Class="Normal"> <A NAME="I1280"></A><A NAME="I1281"></A>All declarations
contain a <I>definition</I> for a <I>view</I> of an entity. A view consists
of an identification of the entity (the entity <I>of</I> the view), plus
view-specific characteristics that affect the use of the entity through
that view (such as mode of access to an object, formal parameter names
and defaults for a subprogram, or visibility to components of a type).
In most cases, a declaration also contains the definition for the entity
itself (a <FONT FACE="Arial, Helvetica">renaming_declaration</FONT> is
an example of a declaration that does not define a new entity, but instead
defines a view of an existing entity (see <A HREF="RM-8-5.html">8.5</A>)).
</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>8</FONT></DIV>
<DIV Class="Normal"> <A NAME="I1282"></A>For each declaration, the
language rules define a certain region of text called the <I>scope</I>
of the declaration (see <A HREF="RM-8-2.html">8.2</A>). Most declarations
associate an <FONT FACE="Arial, Helvetica">identifier</FONT> with a declared
entity. Within its scope, and only there, there are places where it is
possible to use the <FONT FACE="Arial, Helvetica">identifier</FONT> to
refer to the declaration, the view it defines, and the associated entity;
these places are defined by the visibility rules (see <A HREF="RM-8-3.html">8.3</A>).
<A NAME="I1283"></A>At such places the <FONT FACE="Arial, Helvetica">identifier</FONT>
is said to be a <I>name</I> of the entity (the <FONT FACE="Arial, Helvetica">direct_name</FONT>
or <FONT FACE="Arial, Helvetica">selector_name</FONT>); <A NAME="I1284"></A>the
name is said to <I>denote</I> the declaration, the view, and the associated
entity (see <A HREF="RM-8-6.html">8.6</A>). <A NAME="I1285"></A>The declaration
is said to <I>declare</I> the name, the view, and in most cases, the
entity itself.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>9</FONT></DIV>
<DIV Class="Normal"> As an alternative to an <FONT FACE="Arial, Helvetica">identifier</FONT>,
an enumeration literal can be declared with a <FONT FACE="Arial, Helvetica">character_literal</FONT>
as its name (see <A HREF="RM-3-5-1.html">3.5.1</A>), and a function can
be declared with an <FONT FACE="Arial, Helvetica">operator_symbol</FONT>
as its name (see <A HREF="RM-6-1.html">6.1</A>).</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>10</FONT></DIV>
<DIV Class="Normal"> <A NAME="I1286"></A>The syntax rules use the
terms <FONT FACE="Arial, Helvetica">defining_identifier</FONT>, <FONT FACE="Arial, Helvetica">defining_character_literal</FONT>,
and <FONT FACE="Arial, Helvetica">defining_operator_symbol</FONT> for
the defining occurrence of a name; these are collectively called <I>defining
names</I>. <A NAME="I1287"></A>The terms <FONT FACE="Arial, Helvetica">direct_name</FONT>
and <FONT FACE="Arial, Helvetica">selector_name</FONT> are used for usage
occurrences of <FONT FACE="Arial, Helvetica">identifier</FONT>s, <FONT FACE="Arial, Helvetica">character_literal</FONT>s,
and <FONT FACE="Arial, Helvetica">operator_symbol</FONT>s. These are
collectively called <I>usage names</I>. </DIV>
<H4 ALIGN=CENTER>Dynamic Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>11</FONT></DIV>
<DIV Class="Normal"> <A NAME="I1288"></A>The process by which a construct
achieves its run-time effect is called <I>execution</I>. <A NAME="I1289"></A><A NAME="I1290"></A>This
process is also called <I>elaboration</I> for declarations and <I>evaluation</I>
for expressions. One of the terms execution, elaboration, or evaluation
is defined by this International Standard for each construct that has
a run-time effect. </DIV>
<DIV Class="NotesHeader"><FONT SIZE=-1>NOTES</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>12</FONT></DIV>
<DIV Class="Notes"><FONT SIZE=-1>1 <A NAME="I1291"></A>At
compile time, the declaration of an entity <I>declares</I> the entity.
<A NAME="I1292"></A>At run time, the elaboration of the declaration <I>creates</I>
the entity. </FONT></DIV>
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