Computing: How to say “optional parameters”

Question

In programming, a function can have optional parameters, for instance getTemperature() could have an optional parameter "Unit" to say I want the temperature in Kelvin for instance. By default, when specifying no parameter, it would be in Celsius.

How to say optional parameters in Japanese?

ALC says オプションのパラメータ:

Both required and optional parameters are listed.
必須なパラメータおよびオプションのパラメータを列挙します。

But I believe they are wrong, and their translation has a different meaning.

Answer 1

You are looking for

必須（の/な）引数 => required parameter(s).

and

任意（の/な）引数 => optional parameter(s)