n.(biology) a taxonomic category below a class and above an order

Subclassing ?ù subtyping ?ù is-a
An alternative to subclassing
Smalltalk: subclassing subtyping is-a
Subclassing system for computer that operates with portable-executable (PE) modules
Modular reasoning in the presence of subclassing
Traits: An approach to multiple-inheritance subclassing
Traits: An approach to multiple-inheritance subclassing
Object-oriented state machines: subclassing, composition, delegation, and genericity
High-throughput, multiplexed IgG subclassing of antigen-specific antibodies from clinical samples.
Integration of Concurrency Control in a Language with Subtyping and Subclassing