Function unreadable_parts 

pub fn unreadable_parts<R>(id: &str, label: &str, reason: &str) -> ResourceSpec
where
    R: Resource,

The resource tree published for one open document (publish) whose state its holder could not read: its declared actions, APPLY, GROUP and the field edit, each unavailable for reason, so a caller learns why they do not apply instead of finding a hole in the surface. What a state would offer — its children, its views, which actions can be taken now — is not published: there is no state to read it from.