Narrow goal 5.7 to an obvious mistake, and name a wrapper that could grow as none

README.md

@@ -908,10 +908,10 @@ Where the project is heading; the sections before Audience document what ships t
    5. `[SE]` selects one row of a table, and means that row wherever you write it.
    6. If two people could read a template differently, loading it fails, and the
       error shows how to write each meaning.
-   7. A spelling that suggests you meant something else fails to load, and the error
-      shows what to write. Such a spelling holds a part that does nothing where it is
-      written, such as a range with nothing to draw, `int(5,5)`; a default written out
-      is not one.
+   7. Only an obvious mistake fails to load, and the error shows what to write: a part
+      that does nothing where it is written, such as a range with nothing to draw,
+      `int(5,5)`. A default written out, and a wrapper that could grow, such as a list
+      of one, are no mistakes.
    8. When a clearer name turns up, it replaces the old one, even if that needs a new
       major version.
    9. Everything fejkdata renders is written as a template: on the command line, in a