I receive lots of Romanian maps with the projection STEREO70 with Datum "S-42 for ROMANIA". I have only found the "Stereo 1970.prj" by ESRI, and when I open the maps with my GIS software the coordinates do not match. As you can see, the PRJ by ESRI does not work with "S-42", but with "Dealul Piscului 1970":
PROJCS["Stereo_70",GEOGCS["GCS_Dealul_Piscului_1970",DATUM["D_Dealul_Piscului_1970",SPHEROID["Krasovsky_1940",6378245.0,298.3]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Double_Stereographic"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",500000.0],PARAMETER["Central_Meridian",25.0],PARAMETER["Scale_Factor",0.99975],PARAMETER["Latitude_Of_Origin",46.0],UNIT["Meter",1.0],AUTHORITY["EPSG",31700]]
I don't know if anybody is working with Stereo70 + S42 projection and can share their PRJ.