Delete the entire second paragraph as follows:
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+The standard structure type Formula shall not appear between the BT and ET operators delimiting a text object (see 9.4, "Text objects").
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Change the third paragraph as follows:
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+A Formula element may have logical substructure, including other Formula elements.
+For repurposing purposes it may be treated as visually static, without examining its internal contents. It should have a BBox attribute (see 14.8.5, "Standard structure attributes")
+It should have a BBox attribute (see 14.8.5, "Standard structure attributes") and can then for repurposing purposes be treated as visually static, without examining its internal contents.
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...
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