This repository hosts alternative reporting engines to the ones included on Odoo core (RML, QWeb and Webkit). It is complemented with the ones that host the reports theirself:
https://github.com/OCA/account-financial-reporting https://github.com/OCA/purchase-reporting https://github.com/OCA/sale-reporting ...
The convention is to use a suffix to each module to indicate that it's for using with that report engine (for example, account_invoice_report_birt or sale_order_report_pentaho).
It can contain also another utilities directly involved with reports (like merge/split utils, checkers, signing tools and so on).
OCA, or the Odoo Community Association, is a nonprofit organization whose mission is to support the collaborative development of Odoo features and promote its widespread use.