As we evaluate the development priorities for new AZARDI features we always get caught between ePub3 spec features and useful user features. Except for Fixed Layout which is on the anvil at the moment, there are not a lot of compelling market driven reasons at present to pursue ePub3 obscurities and specialities such as CFI.
What we have been asked for is full-text search. So search floated to the top of the development tree.
We have search in our ECMS products, but we needed to start from scratch for this job. Enter DASE - Direct Access Search Engine. It had to be clippy, and work online and offline anywhere.