2.1.4.5 Multiple Escape Characters

A pair of multiple escape characters is used to indicate that an enclosed sequence of characters, including possible macro characters and whitespace[2] characters, are to be treated as alphabetic[2] characters with case preserved. Any single escape and multiple escape characters that are to appear in the sequence must be preceded by a single escape character.

Vertical-bar is a multiple escape character in standard syntax.

2.1.4.5.1 Examples of Multiple Escape Characters