10. A computer system configured to distribute market data, the system comprising: a processor; a computer-readable medium containing computer-executable instructions that, when executed by the processor, cause the system to perform steps comprising: (a) creating at a computer device in real time and on a per message basis a plurality of extensible templates that each that defines a variable length message structure and includes at least one delimiter that is used to identify a repeated group of information and a field outside of a repeating group that specifies the number of occurrences of the group; (b) building a plurality of market data messages that each include variable length fields separated by delimiters and an identification of one of the plurality of extensible templates that defines the message structure used in the message; (c) disseminating a first one of the plurality of extensible templates; and (d) disseminating a first market data message that identifies and is structured in accordance with the first one of the plurality of extensible templates.
13. The system of claim 10 , wherein (a) comprises building a market data message that includes data in a printable character set format.