What comes across, and what stays behind
The name, the birth date and time, the place and its coordinates, the kind of chart, and a Rodden rating where the file carries one. Arcus casts every chart from that birth moment with its own ephemeris rather than copying positions across, so the charts are computed fresh and read the same as one you cast here yourself.
Wheel settings, house system choices and anything you wrote in the other program stay in the other program. Your own settings in Arcus apply to the imported charts.
Importing the same file twice is safe. Charts already in your library are recognised and skipped, so nothing is duplicated and nothing you have edited since is overwritten.
Didn't answer it? Write to support@arcusastrology.com.