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64 MDDL and the Quest for a Market Data Standard
sent. It also requires additional processing by the receiving application, as it will
need to normalize the information before being able to process it.
Just a final point regarding the use of inheritance: whenever possible, always err
on the side of simplicity rather than reducing message size, just because it’s possible.
It’s far better to reduce bandwidth using data compression techniques, examined later
in this book.
MDDL extensions
One of MDDL’s biggest strengths is its extensibility. This is provided by use of the
other container, which is designed so that firms using MDDL could add terms to
meet their specific requirements and that could, at a later stage, easily be migrated
into the standard when the subsequent release was available. The extension process
is easy to use, and it allows for the inheritance of properties and the use of property
types that are defined within the standard itself for example, it’s possible to specify
mdDecimal within an extension. Overall, when compared to other standards in the
market, it scores top marks for extensibility.
So, why do you need to extend? Even though MDDL contains a comprehensive
set of terms, there is always the need to add vendor or end-user specific terms; these
are the icing on the cake, the value-add a vendor can offer.
Polymorphism is the ability to assign a different meaning or usage to something
in different contexts. This technique is used within MDDL, and an example can
be seen in the use of the property, code. It is used to represent the code relating
to an instrument when used within the instrumentIdentifier, or the code of a trad-
ing venue when used within placeOfTrade. It can be also used in the following

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