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<FONT COLOR="#000000"><H1 ALIGN="JUSTIFY"><A NAME="BM14">Section 14</A></H1>
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<H1 ALIGN="JUSTIFY">Predefined language environment</H1>
<P ALIGN="JUSTIFY">This section describes the predefined attributes of VHDL and the packages that all VHDL implementations must provide. </P>
</FONT><H2 ALIGN="JUSTIFY"><A NAME="BM14_1"><A HREF="1076_14.HTM#14.1"><FONT COLOR="#000000">14.1 </FONT></A><FONT COLOR="#000000">Predefined Attributes</A></H2>
<P ALIGN="JUSTIFY">Predefined attributes denote values, functions, types, and ranges associated with various kinds of named entities. These attributes are described below. For each attribute, the following information is provided: </P><DIR>
<P ALIGN="JUSTIFY">-- The kind of attribute: value, type, range, function, or signal. </P>
<P ALIGN="JUSTIFY">-- The prefixes for which the attribute is defined. </P>
<P ALIGN="JUSTIFY">-- A description of the parameter or argument, if one exists. </P>
<P ALIGN="JUSTIFY">-- The result of evaluating the attribute, and the result type (if applicable). </P>
<P ALIGN="JUSTIFY">-- Any further restrictions or comments that apply. </P></DIR>
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<TABLE BORDER CELLSPACING=1 WIDTH=504>
<TR><TD WIDTH="21%" VALIGN="MIDDLE">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY"><A NAME="T_BASE">T'BASE</A></FONT></TD>
<TD WIDTH="40%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Kind:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Type. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Prefix:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Any type or subtype T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">The base type of T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Restrictions:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">This attribute is allowed only as the prefix of the name of another attribute; for example, T'BASE'LEFT. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY"><A NAME="T_LEFT">T'LEFT</A></FONT></TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Kind:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Value. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Prefix:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Any scalar type or subtype T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result Type:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Same type as T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">The left bound of T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY"><A NAME="T_RIGHT">T'RIGHT</A></FONT></TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Kind:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Value. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Prefix:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Any scalar type or subtype T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result Type:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Same type as T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">The right bound of T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY"><A NAME="T_HIGH">T'HIGH</A></FONT></TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Kind:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Value. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Prefix:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Any scalar type or subtype T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result Type:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Same type as T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">The upper bound of T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY"><A NAME="T_LOW">T'LOW</A></FONT></TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Kind:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Value. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Prefix:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Any scalar type or subtype T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result Type:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Same type as T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">The lower bound of T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY"><A NAME="T_ASCENDING">T'ASCENDING</A></FONT></TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Kind:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Value. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Prefix:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Any scalar type or subtype T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result Type:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Type Boolean </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">TRUE if T is defined with an ascending range; FALSE otherwise. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY"><A NAME="T_IMAGE">T'IMAGE(X)</A></FONT></TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Kind:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Function. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Prefix:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Any scalar type or subtype T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Parameter:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">An expression whose type is the base type of T. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result Type:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Type String. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Result:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">The string representation of the parameter value, without leading or trailing whitespace. If T is an enumeration type or subtype and the parameter value is either an extended identifier or a character literal, the result is expressed with both a leading and trailing reverse solidus (backslash) (in the case of an extended identifier) or apostrophe (in the case of a character literal); in the case of an extended identifier that has a backslash, the backslash is doubled in the string representation. If T is an enumeration type or subtype and the parameter value is a basic identifier, then the result is expressed in lowercase characters. If T is a numeric type or subtype, the result is expressed as the decimal representation of the parameter value without underlines or leading or trailing zeros (except as necessary to form the image of a legal literal with the proper value); moreover, an exponent may (but is not required to) be present and the language does not define under what conditions it is or is not present. If the exponent is present, the "e" is expressed as a lowercase character. If T is a physical type or subtype, the result is expressed in terms of the primary unit of T unless the base type of T is TIME, in which case the result is expressed in terms of the resolution limit(see </FONT><A HREF="1076_3.HTM#3.1.3.1"><FONT COLOR="#000000">3.1.3.1 </FONT></A><FONT COLOR="#000000">); in either case, if the unit is a basic identifier, the image of the unit is expressed in lowercase characters. If T is a floating point type or type, the number of digits to the right of the decimal point corresponds to the standard form generated when the DIGITS parameter to TextIO. Write for type REAL is set to 0 (see </FONT><A HREF="1076_14.HTM#14.3"><FONT COLOR="#000000">14.3 </FONT></A><FONT COLOR="#000000">). The result never contains the replacement characters described in </FONT><A HREF="1076_13.HTM#13.10"><FONT COLOR="#000000">13.10 </FONT></A><FONT COLOR="#000000">. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">Restrictions:</FONT></TD>
<TD WIDTH="40%" VALIGN="TOP">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY">It is an error if the parameter value does not belong to the subtype implied by the prefix. </FONT></TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE">
<FONT COLOR="#000000"><P ALIGN="JUSTIFY"><A NAME="T_VALUE">T'VALUE(X)</A></FONT></TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
<TD WIDTH="40%" VALIGN="TOP"> </TD>
</TR>
<TR><TD WIDTH="21%" VALIGN="MIDDLE"> </TD>
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