optionalordefault
optionalordefault is a term used in software design to describe a dual mechanism for handling missing values: a field or parameter may be optional, or it may carry a default value if omitted. It is not a formal keyword in mainstream languages, but appears in design guides and schema definitions as a way to express semantics clearly.
The concept distinguishes two states: absence and default. Optional indicates the value may be omitted entirely,
In practice, implementing optionalordefault requires careful handling to avoid ambiguity between missing values and values set
In API and data modeling contexts, optionalordefault can improve backward compatibility and clarity when evolving interfaces,
See also: optional parameter, default value, JSON Schema, nullability, schema design.