In the document "Using TeX Notation", there are many examples of a code for displaying mathematical notations.
There is a suspicious correspondence of a code with a displayed notation, in the section "Delimiters and Maths Constructs".
(code) \} ⇒ (displayed as) \(x |\}\)
It is necessary to be corrected as
(code) x \} ⇒ (displayed as) \(x \}\) .