求助英语问题

（不要看标题以为我发错板块了）

对于fan-out这个词汇，很多翻译软件将其直接翻译为“扇出”，好像没问题，但用在数据结构这里好像不太合适，我也不明白“扇出”什么意思。

例如：

CPP

It is not (necessarily) binary. Each node has fan-out n + 1, where n is the number of distinct elements.
It can be configured to use large node fan-out, giving it very efficient find performance (albeit at insertion complexity and size).
In some cases, the numerical value of an element is inappropriate. Consider a trie storing DNA strings. It is logical to use a trie with a fan-out of 5 = 1 + |{'A', 'C', 'G', 'T'}|. This requires mapping 'T' to 3, though.
In some cases the keys' iterators are different than what is needed. For example, a trie can be used to search for common suffixes, by using strings' reverse_iterator. As another example, a trie mapping UNICODE strings would have a huge fan-out if each node would branch on a UNICODE character; instead, one can define an iterator iterating over 8-bit (or less) groups.

（摘自https://gcc.gnu.org/onlinedocs/libstdc++/ext/pb_ds/trie_based_containers.html）

首先，我不理解5 = 1 + |{'A', 'C', 'G', 'T'}|是什么，其次，我不理解fan-out的含义。

好像怎么理解都不对的样子，但我朦胧地感觉像是一个类似于输出的东西

有没有大佬解释这里的fan-out可被翻译成什么吗

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