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