SYSML16 — BNF definitions have literals/terminals in italics, which seems to imply that the occurrences of these strings should be in italics, but they are not.

This is probably occurs in many cases, but as an example, see page 40 section 8.3.

<param -prop> ::= ‘ordered’ | ‘unordered’ | ‘unique’ | ‘nonunique’ | ‘seq’ | ‘sequence’

This statement states the the literal "ordered" (and the rest of the list) should be in italics when used on diagrams throughout the spec It is not

BNF definitions have literals/terminals in italics, which seems to imply that the occurrences of these strings should be in italics, but they are not.

Per UML specification formatting conventions all BNF non-terminal symbols must be in italics. This means that terminals should not be in italics.