I was thinking the same 
Oh and one more thing, just to illustrate reliability of different sources http://www.geosrbija.rs/rga/default.aspx?gui=1&lang=3&minX=7545729.4108714&minY=4777564.2247739&maxX=7595664.211563&maxY=4815739.0180561&layers=220%20221&baselayer=100003&visibleOLOverlays=, here you can see same road marked as E80#E752 M25, witch is obviously outdated.
Ok, lets end it where it is. We can correct it if there are mot up to date or reliable information
I know 
but the number of possibilities is probably limited to E-123, E123 and E 123. If everything is in the right relation, than it is not problem in my eyes…But I can fix it if there is standard for Serbia agreed here.
It can also be tagged on the road with int_ref= but you are right, ref= should be the local number.
I think we haven’t agreed (yet) on standard markings for E roads, and since we already have relations for major road and you are building it for regional roads, this might be something to put on a To do list and discuss it later. And ref also, so I’ll leave it as it is .
I just found one more source http://www.unece.org/fileadmin/DAM/trans/conventn/ECE-TRANS-SC1-384e.pdf (E 771 on page 26).
And I’m looking at some examples around Europe and tag combinations are int_ref= for E roads and ref= for national, so this looks ok.
Just a quick ‘2 pare’ :
Seems there is precedent for alpha-2 country code here [1] (uppercase please as prescribed by ISO 3166), and also to keep with the ‘official’ classification [2] maybe we should choose something like
RS:class_I
RS:class_II
although the ‘popular’ classification
RS:national
RS:regional
will work just as well…
[1] http://wiki.openstreetmap.org/wiki/Route#Road_routes
[2] http://en.wikipedia.org/wiki/Highways_in_Serbia
whatever you want. Class I&II would be a better description of the Serbian classifications, national/regional/motoways would be more generic. There is no standard yet in OSM (Germany has no network=, except BAB->Bundesautobahn=Federal motorway, which I think is a mess…a german acronym in an international project). Personally I prefer national/regional/motorways because it is a step forward to an OSM standard and people not familar with Serbian (or Poland or Japan…)specific classifications, will find such generic classes easier and will not need to find the classes for each country individually.
У мају ове године је урађена реорганизација категоризације државних путева.
Законски је регулисана са Уредбом и Правилником:
http://www.putevi-srbije.rs/pdf/regulativa/uredba_o_kategorizaciji_puteva.pdf
http://www.putevi-srbije.rs/pdf/regulativa/pravilnik_objavljen_u_sl_glasniku_rs_broj_50_2012_od_18.05.2012.pdf
У правилнику између осталог стоји:
Po našem zakonu dokumenti državnih ustanova ne mogu piti predmet autorskog prava, počev od zakona i podzakonskih akata pa sve do kartografskih podataka.
Јесте да се удаљавамо од теме, али по ком закону документи државних установа не могу бити предмет ауторског права??? И како дефинишу документ?
Из Закона о ауторским и сродним правима:
Члан 6
Не видим да на основу овог закона да можемо да извучемо неку корист 
Него да се вратимо на тему. Који су подаци потребни за креирање релација, односно за њихову проверу? Ако сам добро разумео то су правац и његова дужина?
http://www.putevi-srbije.rs/index.php?option=com_content&view=category&id=49&lang=sr
На горњем линку се може наћи статистика бројања саобраћаја, односно неке деонице (можда су и све) и њихове дужине. Ајд да се пресаберемо шта нам је потребно па да им то и тражимо.
FYI, just made a new wiki page listing the road route relations (only international so far): http://wiki.openstreetmap.org/wiki/Serbia/Road_network
P.S. Went ahead and did the E65 split all over, took me a couple of days 
the tool OSMonitor is installed. The import is under way. Pawel, the coder of the tool, and I are bit megalomaniac and trying to import the whole planet and keep it current with OSM replication…let’s see. The tool will provide daily reports like this
https://wiki.openstreetmap.org/wiki/User:Ppawel/PolandMajorRoads
However, we need some help for the setup. We need files like these https://github.com/ppawel/osmonitor/tree/master/data/road_refs
i.e. text files for M-roads, E-roads and R-roads with the numbers in it.
I am not sure but I think that there is no more R and M roads.
http://www.putevi-srbije.rs/pdf/regulativa/uredba_o_kategorizaciji_puteva.pdf
I have found some discussion on forum http://www.skyscrapercity.com/showthread.php?t=1168459&page=129 , but right now I am not able to study it.
The number of roads are simply the numbers:
1-6 for IA category
11-36 for IB category
100-181 for II category
not sure I understand. These numbers replace the existing R and M numbers or are just an additional numbering schema? But even if there is a new road numbering, I suggest to start with the old M and R numbers and move to the new schema if it becomes more clear. We also could run reports for both shemas
This isn’t only numbering schema - it is totally different concept of road network in Serbia.
Look at the map: http://www.skyscrapercity.com/showpost.php?p=92155474&postcount=2583
There are a lot of critics about it, but it is the only official categorization.
Any evidence of road signs being replaced already?
Just thinking we should maybe not rush with the work until they are…
The old numbering schema was active for more than 35 years and transition could not be achieved over night - AMSS is still using the old schema.
Look at those links:
http://www.amss.org.rs/index.php?option=com_google&view=standard&id=4&Itemid=181
http://www.putevi-srbije.rs/index.php?option=com_content&view=article&id=2860:130812-radovi-na-drzavnom-putu-ii-reda-broj-128-deonica-golubovac-donji-milanovac&catid=34:odrzavanje&Itemid=1632&lang=sr
http://www.putevi-srbije.rs/index.php?option=com_content&view=article&id=2824:090812-obustava-saobrajaca-na-drzavnom-putu-ii-reda-r-267-ugrinovci-dobanovacka-petlja&catid=26:obustave-saobracaja&Itemid=1584&lang=sr
http://www.putevi-srbije.rs/index.php?option=com_content&view=article&id=2817:080812-drzavni-put-ib-reda-broj-21-m-19-deonica-debrc-misar&catid=26:obustave-saobracaja&Itemid=1581&lang=sr
The M-roads are now in a good shape except M9.1 (missing part in Kosovo), M21.1 (missing part in south Central Serbia), M22.9 (does not exist in reality). The length information come from Wikipedia.rs and I am not sure how outdate the informations are.
https://wiki.openstreetmap.org/wiki/OSMonitor/Serbia_Major_Roads
When the new schema becomes more clear, we can run statistics for it also.