Final answer:
The style used for double spacing in a word-processing document is generally known as the Normal style. This can be adjusted within the style settings of the word processor being used.
Step-by-step explanation:
The style used for double spacing in a document is known as the Normal style. Double spacing refers to the amount of space that appears between lines of text, making the document easier to read. In word processors like Microsoft Word, the Normal style typically defaults to double spacing, but this can be adjusted in the style settings if desired. It's important to note that the exact name of the style can vary depending on the word processor you are using. For instance, some might have a dedicated style for double spacing, while others might require you to adjust the line spacing manually within the Normal or a custom style.