flyspell-tex-command-regexp

flyspell-tex-command-regexp is a variable defined in `flyspell.el'.
Its value is

"\\(\\(begin\\|end\\)[ 	]*{\\|\\(cite[a-z*]*\\|label\\|ref\\|eqref\\|usepackage\\|documentclass\\)[ 	]*\\(\\[[^]]*\\]\\)?{[^{}]*\\)"

Documentation:
A string that is the regular expression that matches TeX commands.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 21.1 of Emacs.