Vehicle registration plates of Bulgaria

Standard Bulgarian vehicle registration plates display black glyphs (alphanumeric characters) on a white background, together with – on the left-hand side of the plate – a blue vertical "EU strip" showing the flag of Europe (or, for older-registered cars, the flag of Bulgaria) and, below it, the country code for Bulgaria: BG.
The characters displayed in the main field of the plate are: 
The format is thus XX NNNN YY, where XX (or X) is the province code, NNNN is the serial number, and YY is the series. Since 1992, only glyphs that are common to both the Cyrillic and the Latin alphabets have been used on Bulgarian plates.
Format.
Letters.
Only 12 letters are used. In Bulgarian order, these are: А, В, Е, К, М, Н, О, Р, С, Т, У, Х. All of these are used as part of the province codes (i.e. on the left). Only nine letters are used in the series (i.e. on the right), of which "А" is the only vowel. The three that are not used in the series, (all vowels) are Е, reserved exclusively for trailers and caravans (e.g. СА 1234 ЕЕ), О and У.
Numbers.
Number plates with a single letter in the series, i.e. "X(X) NNNN Y", appear mainly on mopeds and motorcycles, but can rarely be seen on some older vehicles that have failed to undergo the obligatory re-registration. The format "X(X) AAAAAA" may be used in vanity plates, where "A" represents either letters or numbers chosen by the owner (a name for example). The price of such a custom plate is BGN 7,000 (approx. €3,500), so these are rare.
Other.
Not counting the "Е" series, which is reserved for trailers, nor the vanity plates with no series letters, there is a total of 810,000 possible combinations for each province. This total ran out in Sofia ("С") in late 2005, and was replaced by "СА" in early 2006; In 2014, "CB" began to be used.
Note that the number "0" is written normally, while the letter "O" is egg-shaped.
History.
Until 1958.
Black letters on a white background, in the format: X(x) NN-NN.
1958–1986.
State vehicles retained the black on white format, while private vehicles were given black plates with white lettering. The format was X(x)- NNNN. after reaching 9999 a letter was set in front of the 4 numbers X(x)-Y-NNNN. 
In the early 80's, after all the combinations with the letter "C" were exhausted in Sofia, a new format was introduced in the capital beginning with "A", namely AYY-NNNN. Plates with the combinations AAB-NNNN and ABC-NNNN were issued before the standard was changed once again in 1986.
1986–1992.
A new issue of plates is introduced with the standard format of "X(X) NNNN Y(Y)". Yellow for private plates, white for state-owned vehicles, with previous-style plates no longer valid. These new plates used ISO 7591 standard font & size and had reflective surfaces.
"E" was designated as the series letter for trailers, and "Ч" for private freight and private mass transport vehicles "(Ч: частен, private)"
1992–present.
Since 1992, the letter license plate code used letters common to both the Latin and Cyrillic alphabets, irrespective of whether they have the same phonetic value or not: А, В, Е, К, М, Н, О, Р, С, Т, У, Х, the same as today. A similar system is used in Greece, Russia, Belarus, Bosnia and Herzegovina, and Ukraine. Regions are as per . The new 1992 issue of plates used a white background, in the format "X(X) NNNN Y". All former yellow background plates became invalid. In 1993, The hyphens/stops between letter and number blocks were also phased out and also became invalid in 1993. During the mid-1990s, the "X NNNN Y" combinations began to run out in many provinces (as there were only 90,000 possible combinations), and so a second letter was added to the series. Between 2000 and 2008, the left-hand blue band Bulgaria flag was phased in, eventually becoming a legal requirement on 1 July 2006. These plates were all in the "X(X) NNNN YY" format, but the shape of the letters was changed to the current standard – namely, the letters were made more "square" and heavier-set than previously. These plates all began with the series "AA", thereby repeating some combinations that had already existed before, albeit without the EU strip. On 1 January 2007 Bulgaria (BG) and Romania (RO) joined the European Union, and the standardised Europlate was introduced soon after.
Special types.
Special vehicles.
In use are also three other types of plates in format of "nnn X nnn":
These three types use a white background with black text and a red vertical strip on the right side. Usually, the expiry date is inscribed on the red strip.
Military and police vehicles.
Since 2006, all military vehicles' plates are subject to change with the new ones: the letters "BA" (for Bulgarian Army, formerly "В" in red on a white plate) and 6 digits — the form is "BA NNN NNN".
The same form is adopted for the new license plates of the Civil Protection Service of Bulgaria, beginning with "CP" (for Civil Protection, formerly "ГЗ") followed by 5 digits — "CP NN NNN". On the left side of both kinds of plates there is a blue EU-standard vertical strip.
Foreigner vehicles.
Cars belonging to foreigners and imported into Bulgaria for a limited period of time are light blue with white characters, starting with "ХХ", followed by four (semantically meaningless) digits and two small digits denoting the expiry year. From 2019 "XH" is used after "XX".
Diplomatic plates.
Diplomatic and consular car number plates are similar to ordinary ones, but are recognizably different in their color: white symbols on a red background. Plates starting with "C" indicate diplomatic status, "CC" indicate consular status, while "CT" is used for cars belonging to other staff of diplomatic representations. Additionally, the first two digits of the numeric group represent the country of the diplomatic or consular mission to which the vehicle belongs. Two smaller digits in the lower right corner denote the expiry year of the plate.
Provincial codes.
After the requirement that all number plate codes had to be compatible with both the Cyrillic and Latin alphabets came into force:
External links.
Bulgarian license plates. Info and perso plates. (In Spanish)