In view of the failure of existing methods and the continuing effort of mathematicians to develop a mathematics standard representation, MathML and OpenMath's 2.2 significance and importance increased. Both standards are complementary yet serving different purposes.
The primary purpose of OpenMath is to facilitate reliable communication of mathematical objects between mathematical applications. It ensures semantic content is preserved within the notation. The semantic scope of OpenMath is defined within its content dictionaries (CD) where all symbols used are described in a series of CDs defining their semantic value. Related symbols and functions are grouped into CD groups. It is expected that applications using OpenMath declare which CD groups they understand.
MathML however is World Wide Web oriented in that it seeks to display mathematics on web pages. MathML has two combinable versions, one encoding mathematical objects (presentation markup) and the other encoding mathematical meaning (content markup). Both versions allow authors to encode both the notation which represents a mathematical object and the mathematical structure of the object itself. Moreover, authors can mix both kinds of encoding in order to specify both the presentation and content of a mathematical idea.
In fact there are strong links between both recommendations. The communities developing both standards are closely related, with some members belonging to both groups. This has resulted in both standards superceding each other in some areas.
The core OpenMath CD group is the principal CD group. The core CD group was designed based on MathML 1.0, extending the set of symbols covered by MathML 1.0. Its intention is not to be very specific, only covering everyday and K-12 (kindergarden to high school level) mathematics just as MathML does.
For completeness, a MathML CD group was introduced in the OpenMath standard. It is a subset of the core CD group and has the same semantic scope as do the content elements of MathML. It is expected that most applications will understand the core CD group, automatically understanding the MathML CD group.
The recently published MathML 2.0 version has incorporated elements of the core OpenMath CD group which weren't before in MathML 1.0. But in order to keep the scope of content markup down to a reasonable size, the designers of MathML have restricted the mathematics that it attempts to cover to high school level mathematics limiting MathML's ability to convey mathematical meaning. Because OpenMath is more powerful in this respect, the designers of MathML have introduced means allowing for extensibility. It is possible to encode semantic information inside MathML by embeding OpenMath objects within MathML code.
This demonstrates the close ties existing between both the World Wide Web Consortium and the OpenMath society. In the MathML 2.0 specification one can read: ``The MathML content elements are heavily indebted to the OpenMath project ...''