BX 3.x is upwards compatible with BX 4, which is upwards compatible with BX 5, etc. This means that files save by BX 3.x can be read into BX 4 and BX 5 can read BX 4 save files. You cannot "jump" a level (i.e. have BX 6 directly read in BX 4 based saved files. If you are migrating from an older release, contact your ICS representative and we can arrange for temporary access to the releases you need.