您可以实例化一个新对象并使用箭头表示法来填充文档内的字段。

You would instantiate a new object and use arrow notation to fill in the fields in the document.

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对于后者，可以使用箭头表示法（比如 $doc->new_field），然后通过 storeDoc() 保存更改。

You do this using arrow notation (for example, $doc->new_field), then committing your changes with storeDoc().

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这两个字母是“两次运动的”的缩写，表示箭头所指示的动作要做两次，这种标法在本文的下面几个章节的展示中还会出现。

The letters "DM" which follow some of the illustrations in the text are an abbreviation for "double movement" and indicate that the movement shown by the arrow (s) is to be made twice.

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