为什么 OCaml 项目中的 'hidden' 目录以下划线为前缀?

Why are 'hidden' directories in OCaml projects prefixed with an underscore?

示例是 _opam 和 _build,它们在 OCaml 项目中很常见,令我困惑的是它们不使用通常的点前缀。
这个独特的选择有历史意义吗?

可能出于同样的原因 .vimrc 文件在 Windows 上被调用 _vimrc:

vimrc files in windows generally start with an underscore, "_vimrc" as Windows Explorer won't let you create files starting with a dot. Similarly, the ".vim" directory is called "vimfiles" on windows.

(来自 https://www.reddit.com/r/vim/comments/3v7g86/cant_get_vimrc_working_on_windows/cxkz9nr/