downwardly compatible

All new machines conform to this standard, and can talk to one another, and are downwardly compatible with most surviving Group Two machines.

There were competitive format options offered by the Columbia Broadcasting System that were not downwardly compatible with the existing NTSC format.

Similarly, he feels that by offering it as a no-cost option, the company invalidates the criticism that users will tie themselves into a non-standard technology: since V.32terbo is downwardly compatible with V.32bis, he points out that users are not losing anything by giving themselves the option of faster transmission with V.32terbo.