Question about BlockString term

See http://spec.graphql.org/October2021/#sec-Descriptions :
> To allow GraphQL service designers to easily publish documentation alongside the
capabilities of a GraphQL service, GraphQL descriptions are defined using the
Markdown syntax (as specified by [CommonMark](https://commonmark.org/)). In the
type system definition language, these description strings (often {BlockString})
occur immediately before the definition they describe.

`{BlockString}` is used like a reference to some term but I don't see its definition. I can find only single usage of `BlockString` through the spec. I see `BlockStringCharacter` term and `BlockStringValue` function. I suppose that `{BlockString}` term here is used by mistake and should be changed to just `block string`.