MathML Namespace (temp actualtext moved to content element in new code) \s*(([\-+]?[0-9]*([0-9]\.?|\.[0-9])[0-9]*(r?em|ex|in|cm|mm|p[xtc]|Q|v[hw]|vmin|vmax|%))|0)\s* share with pdf1.7 version from here to end PDF structure Namespace Block Inline Before Start End LrTb RlTb TbRl TbLr LrBt RlBt BtRl BtLr Start Center End Justify Underline Overline LineThrough Sup Sub Normal Unordered Description Disc Circle Square Ordered Decimal UpperRoman LowerRoman UpperAlpha LowerAlpha Document Level Grouping Block Sub Block Inline Ruby Start Center End Justify Distribute Before After Warichu Inline Start Center End Justify Distribute Before After Warichu Inline Start Center End Justify Distribute Lists Tables Before Middle After Justify Start Center End Column Row Both Before Middle After Justify Start Center End Formula Artifact PDF1