Such information may not only be optional, but may not even be relevant for a particular use of it, such as in the retrieve operation where only the member identifier would be required.

这些信息不仅能为可选的，而且甚至还能与其特定用法相关，例如在检索操作中就只需要成员标识符。

youdao

When the member is invoked, optional arguments can be omitted.

在调用该成员时，可选参数可以忽略。

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Returns a string containing the Login server URL for a member, along with the optional information sent to the Login server in the query string.

传回包含成员的登入伺服器url的字串，以及查询字串中传送到登入伺服器的选择性资讯。

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Human spaceflight is an optional programme for Esa member states, and so far the UK has declined to invest in it.

BBC: 'UK spaceman' Nicholas Patrick honoured