In areas where members of the Italian or Hungarian ethnic minorities live alongside members of the Slovene nation, the names of settlements and streets on signs shall be written in both languages. The Slovene name shall be above, that in the minority language below. Both inscriptions shall be the same size.

Source: Report submitted by the Republic of Slovenia pursuant to Art. 25 Para. 1 of the Framework Convention for the Protection of National Minorities
http://www.humanrights.coe.int/minorities/Eng/FrameworkConvention/StateReports/2000/slovenia/slovenia.html#annex2