# C1.CalcEngine.ExpressionEngine.IExpressionSyntax.IdentifierChars

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<h1 id="C1_CalcEngine_ExpressionEngine_IExpressionSyntax_IdentifierChars_" data-uid="C1.CalcEngine.ExpressionEngine.IExpressionSyntax.IdentifierChars*">IdentifierChars Property
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<a id="C1_CalcEngine_ExpressionEngine_IExpressionSyntax_IdentifierChars_" data-uid="C1.CalcEngine.ExpressionEngine.IExpressionSyntax.IdentifierChars*"></a>
<h4 id="C1_CalcEngine_ExpressionEngine_IExpressionSyntax_IdentifierChars" data-uid="C1.CalcEngine.ExpressionEngine.IExpressionSyntax.IdentifierChars">IdentifierChars</h4>
<div class="markdown level1 summary"><p>Gets or sets a string that specifies special characters that are valid for identifiers.</p>
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<h5 class="declaration">Declaration</h5>
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  <pre><code class="lang-csharp hljs">string IdentifierChars { get; set; }</code></pre>
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  <pre><code class="lang-vbnet hljs">Property IdentifierChars As String</code></pre>
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<h5 id="C1_CalcEngine_ExpressionEngine_IExpressionSyntax_IdentifierChars_remarks">Remarks</h5>
<div class="markdown level1 remarks"><p>Identifiers must start with a letter or an underscore, which may be followed by
additional letters, underscores, or digits. This string allows you to specify
additional valid characters such as ':' or '!' (used in Excel range references
for example).</p>
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