"External connection" conduit on DDR2 controller (with ALTMEMPHY)

This is the document you want:

https://www.altera.com/support/literature/lit-external-memory-interface.html

local_init_done indicates when the memory calibration is complete.

local_refresh_ack is only used and needed if you're doing manual auto refresh control of the external memory.

reset_phy_clk_n indicates when the clock used for the PHY is reset.