I noticed that SD generated FPL's through Slovenian airspace will never be accepted because SD uses 'coordinates' rather than official entry/exit points. (I had one unaltered SD generated plan rejected recently for this reason). Slovenian AIP:

REF AIP SLOVENIA ENR 1.10 PARA 1.3. B. SPECIALARANGEMENTS FOR IFR AND VFR FLIGHTS (ICAO NOTIFICATION OF DIFFERENCE) FLIGHTPLANS WITH FLIGHT ROUTES CROSSING FIR LJLA BOUNDARY OR VOLUMES OF CONTROLAIRSPACE SHALL INCLUDE OFFICIALLY PUBLISHED ENTRY/EXIT REPORTING POINTS.COORDINATES OR ANY OTHER NAMES ARE NOT ALLOWED THEREFORE SUCH FPL WILL BEREJECTED.

.. not sure what we can do about that in SD. I guess we have to remember to make manual changes to the plans.

We have already made a change to our data, effective in the next chart update, which should solve this issue. SkyDemon will use the identifiers associated with those VRPs in flightplans.

Sounds good. Will take a look after next update.

yesterday I submitted FP for the route in Slovenia (LJPZ, PE1, Kozina, LJPO, razdrto, Divača, Kozina, PE1, LJPZ). All  points are officially published GAFOR point, or points on VFR recommended route.FP was rejected for the same reason - points were entered as coordinates, and not as a mandatory VFR reporting points, or entry / exit points

The points identified earlier in this thread were five-letter VRPs and therefore compatible with ICAO flightplans. You did not share the flightplan that was generated from your route, but be aware that ICAO designators are NOT valid in ICAO flightplans, and neither are town names, so SkyDemon would definitely have converted those into ICAO-compliant coordinates. You are of course free to reinsert town names before submitting the flightplan but bear in mind that other countries' systems may then reject the flightplan.

can you tell me which part of the FLP I can change, and whether it would be enough to put, in the REMARK section,  route in this form

You can change most of it, including the route section and item 18, which includes any remarks. How you change it is up to you; it is the responsibility of the pilot to get it right.

Have a look on-line for a paper FPL form. You will see that line 15 information is Cruising Speed, Level and Route. As Tim mentioned the route part has to comply with strict formatting requirements and you can't use airfield ICAO codes or VRP names.
The route format typically is a distance and radial from a nav beacon. For example, something like BNE145010.
Other formats are possible but I don't have my reference to hand.
You would have to state your entry crossing points in line 18 (Other Information).
Tony

Just to give additional feedback: My original post here came after I failed to put the entry/exit point names into the route section of an FPL for crossing Slovenian airspace. The FPL was rejected and they asked me for the point names (ALIVO, RADLY). After SD updated the mapping I created the same route again to test it, and it does put the Entry/Exit points like ALIVO and RADLY into the route section, which is what the Slovenian's want according to the ENR exception. So it should be compliant now.

However, I note that SD still puts other 'inland' vfr points (like TREBNJE) in as coordinates. That seems compliant but I'll be interested to know whether such an FPL with mixed names/coordinates gets accepted. It should do because the ENR exception only references entry/exit points being passed as names, but on the phone I had to give names for all the inland vfr points.

There exists a strict definition of what goes where and in which format when you submit a FPL. This is true for VFR and IFR plans. However, VFR FPLs get interpreted by the local authority and are not validated by IFPS at Eurocontrol. Local authorities do exercise quite a bit of liberty and deviate from the internationally defined FPL format. For this reason it is hard to come up with a FPL format which works in all countries.

Most countries want their border crossing and reporting points as they are defined on the respective ICAO map. No ICAO map I know has lat/lon identifiers for VRPs. Every country I fly to accepts the alphanumeric designators as printed on the ICAO map. Therefore it would be nice if SD preferentially used these identifiers and not the (albeit standard and ought-to-be-accepted) lat/lon format.

Greetings, -- Chris.