In a table of contents that has been generated with LaTeX's \tableofcontents command, I would like to add a vertical space before a Chapter item in the table of contents. One way that I have in my notes is to use

\addtocontents{toc}{\protect\vspace{10pt}}


at a desired location in the document so that this gets processed by \tableofcontents to include an appropriate vertical space in the table of contents. I have two questions:

1. Is the above the correct way to get a vertical space in a table of contents?

2. Why is it necessary to use the \protect command here?

Thank you...

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2. \addtocontents writes to the .toc file and this causes commands to be expanded, but you want to write \vspace{10pt} in the .toc file, not the instructions to leave a space (that will be done when the .toc file is read).