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<h1><a name="Annex B">Annex B</a></h1>
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<h1>Glossary</h1>
<h1>(informative)</h1>
<p>This glossary contains brief, informal descriptions for a number of terms and phrases used to define this language. The complete, formal definition of each term or phrase is provided in the main body of the standard.
<p>For each entry, the relevant clause numbers in the text are given. Some descriptions refer to multiple clauses in which the single concept is discussed; for these, the clause number containing the definition of the concept is given in italics. Other descriptions contain multiple clause numbers when they refer to multiple concepts; for these, none of the clause numbers are italicized.
<p><b>B.1 abstract literal:</b> A literal of the <i>universal_real</i> abstract type or the <i>universal_integer</i> abstract type. (§ <a href = "1076_13.HTM#13.2"> 13.2 </a> , <i>§</i> <a href = "1076_13.HTM#13.4"> 13.4 </a> )
<p><b>B.2 access type:</b> A type that provides access to an object of a given type. Access to such an object is achieved by an access value returned by an allocator; the access value is said to <i>designate</i> the object.(<i></i><i>§</i>;3<i>, </i><i>§</i> <a href = "1076_3.HTM#3.3"> 3.3 </a> )
<p><b>B.3 access mode: </b>The mode<i> </i>in which a file object is opened, which can be either <i>read-only</i> or <i>write-only</i>. The access mode depends on the value supplied to the Open_Kind parameter. (<i>§</i> <a href = "1076_3.HTM#3.4.1"> 3.4.1 </a> , § <a href = "1076_14.HTM#14.3"> 14.3 </a> ).
<p><b>B.4 access value:</b> A value of an access type. This value is returned by an allocator and designates an object (which must be a variable) of a given type. A null access value designates no object. An access value can only designate an object created by an allocator; it cannot designate an object declared by an object declaration. (<i>§</i><i>3</i>, § <a href = "1076_3.HTM#3.3"> 3.3 </a> )
<p><b>B.5 active driver:</b> A driver that acquires a new value during a simulation cycle regardless of whether the new value is different from the previous value. (§ <a href = "1076_12.HTM#12.6.2"> 12.6.2 </a> , § <a href = "1076_12.HTM#12.6.4"> 12.6.4 </a> )
<p><b>B.6 actual: </b>An expression, a port, a signal, or a variable associated with a formal port, formal parameter, or formal generic. (§ <a href = "1076_1.HTM#1.1.1.1"> 1.1.1.1 </a> , <i></i><i>§</i><i> <a href = "1076_1.HTM#1.1.1.2"> 1.1.1.2 </a> </i><i>,</i> § <a href = "1076_3.HTM#3.2.1.1"> 3.2.1.1 </a> , § <a href = "1076_4.HTM#4.3.1.2"> 4.3.1.2 </a> , <i></i><i>§</i><i> <a href = "1076_4.HTM#4.3.2.2"> 4.3.2.2 </a> </i><i>, </i>§ <a href = "1076_5.HTM#5.2.1"> 5.2.1 </a> , <i>§</i><i> <a href = "1076_5.HTM#5.2.1.2"> 5.2.1.2 </a> </i>)
<p><b>B.7 aggregate:</b>
<ul>
<p>a) The kind of expression, denoting a value of a composite type. The value is specified by giving the value of each of the elements of the composite type. Either a positional association or a named association may be used to indicate which value is associated with which element.
<p>b) A kind of target of a variable assignment statement or signal assignment statement assigning a composite value. The target is then said to <i>be in the form of an aggregate</i>. (§ <a href = "1076_7.HTM#7.3.1"> 7.3.1 </a> , <i></i><i>§</i><i> <a href = "1076_7.HTM#7.3.2"> 7.3.2 </a> </i><i>, </i>§ <a href = "1076_7.HTM#7.3.4"> 7.3.4 </a> , § <a href = "1076_7.HTM#7.3.5"> 7.3.5 </a> , § <a href = "1076_7.HTM#7.5.2"> 7.5.2 </a> )
</ul>
<p><b>B.8 alias: </b> An alternate name for a named entity. (§ <a href = "1076_4.HTM#4.3.3"> 4.3.3 </a> )
<p><b>B.9 allocator:</b> An operation used to create anonymous, variable objects accessible by means of <i>access values</i>. (<i>§</i> <a href = "1076_3.HTM#3.3"> 3.3 </a> , § <a href = "1076_7.HTM#7.3.6"> 7.3.6 </a> )
<p><b>B.10 analysis:</b> The syntactic and semantic analysis of source code in a VHDL design file and the insertion of intermediate form representations of design units into a design library. (§ <a href = "1076_11.HTM#11.1"> 11.1 </a> , § <a href = "1076_11.HTM#11.2"> 11.2 </a> , § <a href = "1076_11.HTM#11.4"> 11.4 </a> )
<p><b>B.11 anonymous:</b> The undefined simple name of an item, which is created implicitly. The base type of a numeric type or an array type is anonymous;similarly, the object denoted by an access value is anonymous. (§ <a href = "1076_4.HTM#4.1"> 4.1 </a> )
<p><b>B.12 appropriate:</b> A prefix is said to be appropriate for a type if the type of the prefix is the type considered, or if the type of the prefix is an access type whose designated type is the type considered.(§ <a href = "1076_6.HTM#6.1"> 6.1 </a> )
<p><b>B.13 architecture body: </b> A body associated with an entity declaration to describe the internal organization or operation of a design entity. An architecture body is used to describe the behavior, data flow, or structure of a design entity. (§1, <i>§</i> <a href = "1076_1.HTM#1.2"> 1.2 </a> )
<p><b>B.14 array object: </b>An object of an array type.(<i></i><i>§</i>3<i>)</i>
<p><b>B.15 array type: </b>A type, the value of which consists of elements that are all of the same subtype (and hence, of the same type). Each element is uniquely distinguished by an index (for a one-dimensional array) or by a sequence of indexes (for a multidimensional array). Each index must be a value of a discrete type and must lie in the correct index range. (§ <a href = "1076_3.HTM#3.2.1"> 3.2.1 </a> )
<p><b>B.16 ascending range:</b> A range L <b>to</b> R. (§ <a href = "1076_3.HTM#3.1"> 3.1 </a> )
<p><b>B.17 ASCII:</b> The American Standard Code for Information Interchange. The package Standard contains the definition of the type Character, the first 128 values of which represent the ASCII character set. (§ <a href = "1076_3.HTM#3.1.1"> 3.1.1 </a> , <i>§</i>; <a href = "1076_14.HTM#14.2"> 14.2 </a> )
<p><b>B.18 assertion violation:</b> A violation that occurs when the condition of an assertion statement evaluates to false. (§ <a href = "1076_8.HTM#8.2"> 8.2 </a> )
<p><b>B.19 associated driver:</b> The single driver for a signal in the (explicit or equivalent) process statement containing the signal assignment statement.(<a name="1076_12.html# <a href = "1076_12.HTM#12.6.1"> 12.6.1 </a> ">§ <a href = "1076_12.HTM#12.6.1"> 12.6.1 </a> </a>)
<p><b>B.20 associated in whole:</b> When a single association element of a composite formal supplies the association for the entire formal.(§ <a href = "1076_4.HTM#4.3.2.2"> 4.3.2.2 </a> )
<p><b>B.21 associated individually:</b> A property of a formal port, generic, or parameter of a composite type with respect to some association list. A composite formal whose association is defined by multiple association elements in a single association list is said to be<i> associated individually </i>in that list. The formats of such association elements must denote non-overlapping subelements or slices of the formal. (§ <a href = "1076_4.HTM#4.3.2.2"> 4.3.2.2 </a> )
<p><b>B.22 association element:</b> An element that associates an actual or local with a local or formal. (§ <a href = "1076_4.HTM#4.3.2.2"> 4.3.2.2 </a> )
<p><b>B.23 association list:</b> A list that establishes correspondences between formal or local port or parameter names and local or actual names or expressions. (§ <a href = "1076_4.HTM#4.3.2.2"> 4.3.2.2 </a> )
<p><b>B.24 attribute:</b> A definition of some characteristic of a named entity. Some attributes are predefined for types, ranges, values, signals, and functions. The remaining attributes are user defined and are always constants.(§ <a href = "1076_4.HTM#4.4"> 4.4 </a> )
<p><b>B.25 base specifier:</b> A lexical element that indicates whether a bit string literal is to be interpreted as a binary, octal, or hexadecimal value.(§ <a href = "1076_13.HTM#13.7"> 13.7 </a> )
<p><b>B.26 base type:</b> The type from which a subtype defines a subset of possible values, otherwise known as a <i>constraint</i>. This subset is not required to be proper. The base type of a type is the type itself. The base type of a subtype is found by recursively examining the type mark in the subtype indication defining the subtype. If the type mark denotes a type, that type is the base type of the subtype; otherwise, the type mark is a subtype,and this procedure is repeated on that subtype. (§3) <i> See also</i> <b>subtype</b>.
<p><b>B.27 based literal:</b> An abstract literal expressed in a form that specifies the base explicitly. The base is restricted to the range 2 to 16.(§ <a href = "1076_13.HTM#13.4.2"> 13.4.2 </a> )
<p><b>B.28 basic operation:</b> An operation that is inherent in one of the following:
<ul>
<p>a) An assignment (in an assignment statement or initialization);
<p>b) An allocator;
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