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EXISTS: scoping restriction
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‎spec/index.html‎

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@@ -8730,10 +8730,10 @@ <h4>Variable Scope</h4>
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query. The definition below provides a way of determining this from the
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abstract syntax tree of a query.</p>
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<p>Note that a subquery with a projection can hide variables; use of a variable in
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<code>FILTER</code> or in <code>MINUS</code> does not cause the variable to be in-scope
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`FILTER` or in `MINUS` does not cause the variable to be in-scope
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outside of those forms.</p>
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<p>Let <b>P</b>, <b>P1</b>, and <b>P2</b> be graph patterns, and <b>E</b>,
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<b>E1</b>,..., through <b>En</b> be expressions. A variable <code>v</code> is in-scope if:</p>
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<b>E1</b>,..., through <b>En</b> be expressions. A variable `v` is in-scope if:</p>
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<table style="border-collapse: collapse; border-color: #000000; border-spacing:5px; border-width: 1px">
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<tbody>
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<tr>
@@ -8742,70 +8742,81 @@ <h4>Variable Scope</h4>
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</tr>
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<tr>
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<td>Basic Graph Pattern (BGP)</td>
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<td><code>v</code> occurs in the BGP</td>
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<td>`v` occurs in the BGP</td>
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</tr>
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<tr>
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<td>Path</td>
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<td><code>v</code> occurs in the path</td>
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<td>`v` occurs in the path</td>
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</tr>
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<tr>
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<td>Group <code>{ P1 P2 ... }</code></td>
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<td><code>v</code> is in-scope if it is in-scope in one or more of P1, P2, ...</td>
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<td>Group `{ P1 P2 ... }`</td>
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<td>`v` is in-scope if it is in-scope in one or more of P1, P2, ...</td>
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</tr>
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<tr>
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<td><code>GRAPH term { P }</code></td>
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<td><code>v</code> is <code>term</code> or <code>v</code> is in-scope in P</td>
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<td>`GRAPH term { P }`</td>
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<td>`v` is `term` or `v` is in-scope in P</td>
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</tr>
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<tr>
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<td><code>{ P1 } UNION { P2 }</code></td>
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<td><code>v</code> is in-scope in P1 or in-scope in P2</td>
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<td>`{ P1 } UNION { P2 }`</td>
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<td>`v` is in-scope in P1 or in-scope in P2</td>
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</tr>
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<tr>
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<td><code>OPTIONAL {P}</code></td>
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<td><code>v</code> is in-scope in P</td>
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<td>`OPTIONAL {P}`</td>
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<td>`v` is in-scope in P</td>
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</tr>
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<tr>
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<td><code>SERVICE term {P}</code></td>
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<td><code>v</code> is <code>term</code> or <code>v</code> is in-scope in P</td>
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<td>`SERVICE term {P}`</td>
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<td>`v` is `term` or `v` is in-scope in P</td>
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</tr>
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<tr>
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<td><code>BIND (expr AS v)</code></td>
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<td><code>v</code> is in-scope</td>
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<td>`BIND (expr AS v)`</td>
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<td>`v` is in-scope</td>
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</tr>
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<tr>
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<td><code>SELECT .. v .. { P }</code></td>
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<td><code>v</code> is in-scope</td>
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<td>`SELECT .. v .. { P }`</td>
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<td>`v` is in-scope</td>
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</tr>
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<tr>
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<td><code>SELECT ... (expr AS v)</code></td>
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<td><code>v</code> is in-scope</td>
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<td>`SELECT ... (expr AS v)`</td>
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<td>`v` is in-scope</td>
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</tr>
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<tr>
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<td><code>GROUP BY (expr AS v)</code></td>
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<td><code>v</code> is in-scope</td>
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<td>`GROUP BY (expr AS v)`</td>
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<td>`v` is in-scope</td>
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</tr>
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<tr>
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<td><code>SELECT * { P }</code></td>
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<td><code>v</code> is in-scope in <code>P</code></td>
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<td>`SELECT * { P }`</td>
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<td>`v` is in-scope in `P`</td>
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</tr>
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<tr>
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<td><code>VALUES v { values }</code></td>
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<td><code>v</code> is in-scope</td>
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<td>`VALUES v { values }`</td>
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<td>`v` is in-scope</td>
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</tr>
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<tr>
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<td><code>VALUES varlist { values }</code></td>
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<td><code>v</code> is in-scope if <code>v</code> is in <code>varlist</code></td>
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<td>`VALUES varlist { values }`</td>
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<td>`v` is in-scope if `v` is in `varlist`</td>
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</tr>
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<tr>
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<td>`EXISTS` and `NOT EXISTS`</td>
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<td>
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`v` is in-scope if it is in-scope for the
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<a href="#defn_sparqlSolutionMapping">solution mapping</a>
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where the expression containing `EXISTS` or `NOT EXISTS` is applied.
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</td>
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</tr>
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</tbody>
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</table>
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<p>The variable <code>v</code> must not be in-scope at the point of the <code>(expr AS
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v)</code> form. The scoping for <code>(expr AS v)</code> applies immediately in
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<code>SELECT</code> expressions.</p>
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<p>In <code>BIND (expr AS v)</code> requires that the variable <code>v</code> is not
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in-scope from the preceeding elements in the group graph pattern in which it is used.</p>
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<p>In <code>SELECT</code>, the variable <code>v</code> must not be in-scope in the graph
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pattern of the <code>SELECT</code> clause, nor used in another select expression earlier in
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the clause.</p>
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<p>The variable `v` must not be in-scope at the point of the
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`(expr AS v)` form. The scoping for `(expr AS v)`
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applies immediately in `SELECT` expressions.
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</p>
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<p>In `BIND (expr AS v)` requires that the variable `v` is not
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in-scope from the preceeding elements in the group graph pattern in which it is used.
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</p>
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<p>In `SELECT`, the variable `v` must not be in-scope in the graph
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pattern of the `SELECT` clause, nor used in another select expression earlier in
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the clause.
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</p>
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</section>
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<section id="convertGraphPattern">
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<h4>Converting Graph Patterns</h4>
@@ -10971,52 +10982,95 @@ <h3>Grammar</h3>
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section 6 <a data-cite="xml11#sec-notation">Notation</a>.</p>
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<p>Notes:</p>
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<ol>
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<li>Keywords are matched in a case-insensitive manner with the exception of
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the keyword '<code>a</code>' which, in line with Turtle and N3, is used
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in place of the IRI <code>rdf:type</code>
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(in full, <code><a href="http://www.w3.org/1999/02/22-rdf-syntax-ns#type">http://www.w3.org/1999/02/22-rdf-syntax-ns#type</a></code>).</li>
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<li>Escape sequences are case sensitive.</li>
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<li>When tokenizing the input and choosing grammar rules, the longest match is chosen.</li>
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<li>The SPARQL grammar is LL(1) when the rules with uppercased names are used as terminals.</li>
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<li>There are two entry points into the grammar: <code>QueryUnit</code> for the SPARQL query language
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and <code>UpdateUnit</code> for the SPARQL update language.</li>
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<li>In signed numbers, no white space is allowed between the sign and the number.
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<li>
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Keywords are matched in a case-insensitive manner with the exception of
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the keyword '`a`' which, in line with Turtle and N3, is used
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in place of the IRI `rdf:type` (in full,
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<code><a href="http://www.w3.org/1999/02/22-rdf-syntax-ns#type">http://www.w3.org/1999/02/22-rdf-syntax-ns#type</a></code>).
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</li>
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<li>
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Escape sequences are case sensitive.
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</li>
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<li>
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When tokenizing the input and choosing grammar rules, the longest match is chosen.
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</li>
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<li>
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The SPARQL grammar is LL(1) when the rules with uppercased names are used as terminals.
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</li>
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<li>
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There are two entry points into the grammar: `QueryUnit` for the SPARQL query language
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and `UpdateUnit` for the SPARQL update language.
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</li>
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<li>
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In signed numbers, no white space is allowed between the sign and the number.
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The <code><a href="#rAdditiveExpression">AdditiveExpression</a></code> grammar rule allows for this by
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covering the two cases of an expression followed by a signed number. These
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produce an addition or subtraction of the unsigned number as appropriate.</li>
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<li>The tokens <code><a href="#rInsertData">INSERT DATA</a></code>,
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produce an addition or subtraction of the unsigned number as appropriate.
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</li>
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<li>
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The tokens <code><a href="#rInsertData">INSERT DATA</a></code>,
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<code><a href="#rDeleteData">DELETE DATA</a></code> and
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<code><a href="#rDeleteWhere">DELETE WHERE</a></code> allow any amount of white space between the words.
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The single space version is used in the grammar for clarity.</li>
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<li>The <code><a href="#rQuadData">QuadData</a></code> and
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The single space version is used in the grammar for clarity.
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</li>
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<li>
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The <code><a href="#rQuadData">QuadData</a></code> and
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<code><a href="#rQuadPattern">QuadPattern</a></code>
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rules both use rule <code><a href="#rQuads">Quads</a></code>. The rule
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<code><a href="#rQuadData">QuadData</a></code>, used in
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<a href="#rInsertData"><code>INSERTDATA</code></a> and
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<a href="#rDeleteData"><code>DELETE DATA</code></a>,
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must not allow variables in the quad patterns.</li>
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<li>Blank node syntax is not allowed in <code><a href="#rDeleteWhere">DELETE WHERE</a></code>,
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must not allow variables in the quad patterns.
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</li>
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<li>
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Blank node syntax is not allowed in <code><a href="#rDeleteWhere">DELETE WHERE</a></code>,
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the <code><a href="#rDeleteClause">DeleteClause</a></code> for
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<code>DELETE</code>,
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nor in <code><a href="#rDeleteData">DELETE DATA</a></code>.</li>
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<li>Rules for limiting the use of blank node identifiers are given in <a href="#grammarBNodes">section 19.6</a>.</li>
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<li>The number of variables in the variable list of <code>VALUES</code> block
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must be the same as the number of each list of associated values in the <code>DataBlock</code>.</li>
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<li>Variables introduced by <code>AS</code> in a <code>SELECT</code> clause
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must not already be <a href="#variableScope">in-scope</a>.</li>
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<li>The variable assigned in a <code>BIND</code> clause must not be already
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nor in <code><a href="#rDeleteData">DELETE DATA</a></code>.
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</li>
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<li>
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Rules for limiting the use of blank node identifiers are given in
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<a href="#grammarBNodes">section 19.6</a>.
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</li>
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<li>
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The number of variables in the variable list of <code>VALUES</code> block
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must be the same as the number of each list of associated values in the
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<code>DataBlock</code>.
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</li>
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<li>
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Variables introduced by <code>AS</code> in a <code>SELECT</code> clause
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must not already be <a href="#variableScope">in-scope</a>.
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</li>
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<li>
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The variable assigned in a <code>BIND</code> clause must not be already
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in-use within the immediately preceding <code><a href="#rTriplesBlock">TriplesBlock</a></code> within a
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<code><a href="#rGroupGraphPattern">GroupGraphPattern</a></code>.</li>
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<li>Aggregate functions can be one of the
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<code><a href="#rGroupGraphPattern">GroupGraphPattern</a></code>.
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</li>
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<li>
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Aggregate functions can be one of the
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<a href="#rAggregate">built-in keywords for aggregates</a>
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or a custom aggregate, which is syntactically a <a href="#rFunctionCall">function
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call</a>. Aggregate functions may only be used in
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or a custom aggregate, which is syntactically a
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<a href="#rFunctionCall">function call</a>.
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Aggregate functions may only be used in
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<a href="#rSelectClause">SELECT</a>, <a href="#rHavingClause">HAVING</a>
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and <a href="#rOrderClause">ORDER BY</a> clauses.</li>
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<li>The expression argument of an aggregate function can not contain an aggregate function.</li>
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<li>Only custom aggregate functions use the <code>DISTINCT</code> keyword
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in a <a href="#rFunctionCall">function call</a>.</li>
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<li>A <a href="#rReifier">reifier</a> or
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and <a href="#rOrderClause">ORDER BY</a> clauses.
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</li>
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<li>
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Any variable that is assigned to in the graph pattern of `EXISTS` or `NOT EXISTS`
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must not be <a href="#variableScope">in-scope</a>. This applies to `BIND`,
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variables introduced by `AS` in a `SELECT` clause,
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variables introduced by `AS` in `GROUP BY`,
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and variables in a `VALUES` clause.
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</li>
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<li>
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The expression argument of an aggregate function can not contain an aggregate function.
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</li>
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<li>
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Only custom aggregate functions use the <code>DISTINCT</code> keyword
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in a <a href="#rFunctionCall">function call</a>.
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</li>
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<li>
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A <a href="#rReifier">reifier</a> or
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<a href="#rAnnotationBlockPath">annotation syntax</a>
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is only permitted after a triple when the property position is
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a simple path (an IRI, the keyword <code>a</code>, or a variable),

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