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      <td valign="top"><apll>Z←L~R</apll></td>
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      <td>returns a subset of <apll>L</apll> consisting of those elements in <apll>L</apll> which do not occur in <apll>R</apll>.</td>
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  <td><apll>L</apll> is a scalar or vector, else signal <apll>RANK ERROR</apll>.</td>
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  <td><apll>R</apll> is an arbitrary array.</td>
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  <td><apll>Z</apll> is a vector identical to <apll>(~L∊R)/L</apll>.</td>
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  <td>The result is sensitive to <apll>⎕CT</apll>.</td>
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<p>This feature is implemented by an internal magic function:</p>

<apll>&nbsp;&nbsp;&nbsp;&nbsp;{del}&nbsp;Z←L #DydTilde R</apll><br />
<apll>[1]&nbsp;&nbsp;&nbsp;Z←(~L∊R)/L</apll><br />
<apll>&nbsp;&nbsp;&nbsp;&nbsp;{del}</apll>