Since there is more then one rail on double track, some rail is named addiational(eg upline) to the line name(eg Paris-London Line) for rail repair/operation etc.
Railway:direction and oneway isn’t useful since it require thinking which is up+it might call inbound/3rd line/express line/track etc.
So saionji thought “railway:infra_name=xxx line upline”for the new tag, welcome to discuss. (some line itself might call “name=xxx upline”)