`†` in `an+b` definition

[romainmenke]

data/css/syntaxes.json

Line 15 in 10199d7

"syntax": "odd | even | <integer> | <n-dimension> | '+'?† n | -n | <ndashdigit-dimension> | '+'?† <ndashdigit-ident> | <dashndashdigit-ident> | <n-dimension> <signed-integer> | '+'?† n <signed-integer> | -n <signed-integer> | <ndash-dimension> <signless-integer> | '+'?† n- <signless-integer> | -n- <signless-integer> | <n-dimension> ['+' | '-'] <signless-integer> | '+'?† n ['+' | '-'] <signless-integer> | -n ['+' | '-'] <signless-integer>"

https://drafts.csswg.org/css-syntax/#anb-plus

I might be mistaken but the † seems to only be a marker to a note and not part of the definition?