last place; lowest position; lowest rank; least significant (bit); lowest order
upward compatible; forward compatible; compatible with input or components intended for higher tier or later systems, versions, etc.; downward compatible; backward compatible; compatible with input or components intended for lower tier or older systems, versions, etc.
person of low rank or position
upward compatibility; forward compatibility; compatibility with input or components intended for higher tier or later systems, versions, etc.; downward compatibility; backward compatibility; compatibility with input or components intended for lower tier or older systems, versions, etc.
subcategorization; subcategorisation