For the language code for Moldova, use mol if written in Cyrillic, but if it is a modern work and is written in the Latin script, use rum.

"The majority of the people of Moldova are ethnic Romanians, and the native language of Moldova is Romanian. In the so-called Transdniester region, east of the Dniester River, however, there are large numbers of Russians and Ukrainians (who rebelled against Moldovan authority in 1992). A national law passed in 1989 requires use of the Latin alphabet and the Romanian language."
Encyclopedia Britannica (On-line Version)

Related Topics:
List of Language Codes