The following is the XML Parser for C default behavior:
Character set encoding is UTF-8. If all your documents are ASCII, you are encouraged to set the encoding to US-ASCII for better performance.
Messages are printed to stderr unless msghdlr is given.
A parse tree which can be accessed by DOM APIs is built unless saxcb is set to use the SAX callback APIs. Note that any of the SAX callback functions can be set to NULL if not needed.
The default behavior for the parser is to check that the input is well-formed but not to check whether it is valid. The flag XML_FLAG_VALIDATE can be set to validate the input. The default behavior for whitespace processing is to be fully conformant to the XML 1.0 spec, that is, all whitespace is reported back to the application but it is indicated which whitespace is ignorable. However, some applications may prefer to set the XML_FLAG_DISCARD_WHITESPACE which will discard all whitespace between an end-element tag and the following start-element tag.
It is recommended that you set the default encoding explicitly if using only single byte character sets (such as US-ASCII or any of the ISO-8859 character sets) for performance up to 25% faster than with multibyte character sets, such as UTF-8.