An element composed of other elements is a parent element with child elements.
Child elements are linked to their parent element through a group particle.
![](../image/penoba1314176319318_19-rad1232636788145.image)
There are three kinds of group particles:
Tool
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Symbol
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Description
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![](../image/penoba1314176319318_19-rad1232636791614.image)
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Sequence - Child elements must appear at least once in the order of their declaration
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![](../image/penoba1314176319318_19-rad1232636794755.image)
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Choice - Only one child element can be linked to the parent element
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![](../image/penoba1314176319318_19-rad1232636797989.image)
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All - Child elements can appear in any order and each of them once or not at all
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These particles translate to the following tags in each of the supported languages:
Group Particle
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XSD
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XDR (order attribute)
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DTD (separator)
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Sequence
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<sequence>
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seq
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, (comma)
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Choice
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<choice>
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one
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| (bar)
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All
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<all>
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many
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, (comma)
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