ANYQUOTE and QUOTE

<ANYQUOTE> and <QUOTE> symbols are used to allow for pairs of double quotes or pairs of single quotes.

This mechanism is needed, for example, to allow for both double-quote pairs and single-quote pairs for the attributes in XML data.

During the data validation process, the <ANYQUOTE> symbol can match both double and single quote characters, and <QUOTE> must match the same quote character (single or double) that was recognized by the last <ANYQUOTE> symbol.

This logic is used to allow for pairs of matching double or single quotes and to prevent the pairs with mixed double and single quotes.