H5O_SET_COMMENT sets the comment for the specified object to the contents of
comment. Any previously existing comment is overwritten.
The target object is specified by an identifier,
comment is the empty string or a null pointer, any existing comment message is removed from the object.
Comments should be relatively short, null-terminated, ASCII strings.
Comments can be attached to any object that has an object header. Datasets, groups, and committed (named) datatypes have object headers. Symbolic links do not have object headers.
If a comment is being added to an object attribute, this comment will be attached to the object to which the attribute belongs and not to the attribute itself.