org-calendar-insert-diary-entry-key

org-calendar-insert-diary-entry-key is a variable defined in `org.el'.
Its value is

[105]

Documentation:
The key to be installed in `calendar-mode-map' for adding diary entries.
This option is irrelevant until `org-agenda-diary-file' has been configured
to point to an Org-mode file. When that is the case, the command
`org-agenda-diary-entry' will be bound to the key given here, by default
`i'. In the calendar, `i' normally adds entries to `diary-file'. So
if you want to continue doing this, you need to change this to a different
key.

You can customize this variable.