Airbus:
D indicates a radial but it doesn't always tell you from where. On SIDS and STARS you often have to consult the relevant DEP or ARR chart to find out to which navaid it is referenced. AS VCP says, the final letter of the group indicates a range in NM taken from your MCDU keypad so E = 5 miles, J = 10 miles etc and so forth.
CI = centreline intercept for ILS approach
FF = Final approach fix
For non-precision approaches, CD, FD and MD are used.
Occasionally, approach and/or go-around coding may not use the same navaids as the approach plate leading to momentary thinks-bubbles.
I have seen an explanation but I can't recall where and I can't find it.
HTH,
WS