noun
internal procedure
Computing term for a procedure defined and used within a program or system, not exposed externally.
この関数は内部手続として実装されている。
This function is implemented as an internal procedure.
外部手続 is an external procedure, accessible from outside the defining module, while 内部手続 is internal and hidden.
Compound of 内部 (internal) and 手続 (procedure), a straightforward technical term.