A nonterminal symbol represents a syntactic category, which defines one or more valid phrasal or sentence structure consisted of an n-element subset.
One variation to the standard convention for denoting nonterminals and terminals is to remove metasymbols such as angle brackets and quotations and apply font types to the intended words.
In terms of simplicity, BNF's metanotation definitely does not help to make the metasyntax easier-to-read as the open-end and close-end metasymbols appear too abundantly.
The extended metasyntax utilizes properties such as case, font, and code position of characters to reduce unnecessary aforementioned complexity.
Moreover, some metalanguages use fonted separator categories to incorporate metasyntactic features for layout conventions, which are not formally supported by BNF.