One of the possibly more under-appreciated features of DITA 1.2 is the <coderef> element. A <coderef> lets you include the content of a non-DITA code file within a <codeblock> element. Using a <coderef> can help to ensure the accuracy of your documentation by including real working code samples.
DITA-FMx 2.0 provides complete support for the <coderef> element. (Default FM-DITA does not support this feature.) This video provides a quick (2.5 minute) tour of authoring and publishing. For publishing, it demonstrates the use of the CodeFormatter plugin for providing syntax-based formatting of code samples in DITA-FMx.