This is the language reference category.
“Sum-class symbols, or accumulation symbols, are symbols whose sub- and superscripts appear...Sum-class symbol
“A LaTeX environment is one of the following: Text inside a float environment is "floated...List of LaTeX environments
“The preamble is the first section of an input file, before the text of the document itself, in...LaTeX preamble
This category has the following 3 subcategories, out of 3 total.