In the SCM 12.6 bookshelf, information about BIRT reports can be found in the Workbench User Guide:
Chapter 4: Setting Preferences - Set BIRT Preferences on p. 54
Chapter 13: Finding Objects and Reporting - Custom Reports on p. 260
Chapter 13: Finding Objects and Reporting - BIRT Report Viewer on p. 263
Let me know if this helps.
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