Updating Delete Filter

Hi All,

We want to work on customizing delete functionality and i had few questions regarding that, Please help me on that:

1. I understand that filter postDocHistoryInfo allows you to work on customizing delete functionality. But how do i know that user selected delete option and not other options in this filter

2. Also how do i make OWCC understand that i have created a filter for postDocHistoryInfo, where should i mention that?

3. I also want to check few metadata of the document before i move the document, how do i get a reference to the document as well as what API's can be used to get metadata?