Microsoft Core XML Services 6.0 / 4.0 SP3 3 1.0

MSXML 6.0 (MSXML6) has improved reliability, security, conformance with the XML 1.0 and XML Schema 1.0 W3C Recommendations, and compatibility with System.Xml 2.0.

The Microsoft Core XML Services (MSXML) 6.0 package provides standards-conformant implementations of:
- XML 1.0 (DOM & SAX2 APIs)
- XML Schema (XSD) 1.0
- XPath 1.0
- XSLT 1.0

In addition, it offers client and server-safe components for XML over HTTP. MSXML6 is also the first version of MSXML to provide a 64-bit redistributable package.

MSXML6 has made significant improvements over previous versions of MSXML in the following areas:
- Reliability - MSXML6 has addressed a significant number of stability issues particularly in resource-constrained scenarios.
- Security – MSXML6 uses the principle of “off-by-default” to make loading XML data from anonymous or untrusted sources more secure. This may mean that upgrades from MSXML3 and MSXML4 will need to re-configure the MSXML6 components using SetProperty and/or SetFeature as appropriate.
- W3C Conformance and System.Xml 2.0 Compatibility – MSXML6 has gone through extensive testing and a number of issues have been addressed to improve W3C conformance and System.Xml 2.0 compatibility particularly in terms of the XML Schema 1.0 Recommendation.

MSXML6 is intended as an upgrade path for existing MSXML3 and MSXML4 users except for users that leverage some of the older ProgIDs and technologies in MSXML3 and MSXML4. The following are not supported in MSXML6:
- DSOControl
- XML Data Islands
- XMLHTTP10, DOMDocument10, FreeThreadedDOMDocument10
- XDR Schemas

MSXML 4.0 Service Pack 3 (SP3) is a complete replacement of MSXML 4.0, MSXML 4.0 Service Pack 1 (SP1) and MSXML 4.0 Service Pack 2 (SP2). MSXML 4.0 SP3 provides a number of security and reliability bug fixes. Support will end for MSXML 4.0 SP2 in November 2009