* by default, the standard Java [http://download.oracle.com/javase/6/docs/api/javax/xml/parsers/SAXParser.html SAXParser] is used to parse the input XML documents. Some documents may not be fully processed by the default parser. This may e.g. be the case if they are too large or contain too many or incorrect entities.
* the internal, built-in XML parser of BaseX is more fault-tolerant than the default parser, and supports standard HTML entities out-of-the-box, and is faster in most cases. In turn, it does not support all peculiarities introduced oddities specified by DTDs, and cannot resolve [[Catalog_Resolver|catalogs]].
===GUI===