Name the relative-sigil rejection where the quick start points, and the struct field a null prefix needs

CHANGELOG.md

@@ -53,7 +53,8 @@ replacement, and each removed path, column or flag.
   ranges the SSA assigns and carries the columns `area`, `group` and `serial`, so
   `--format csv en_US.ssn` writes a header where it used to fail; `en_US.itin` is new
   and carries the same three. `person.prefix` is null where a person has no title,
-  where it used to be an empty string, so `--format sql` writes `NULL`.
+  where it used to be an empty string, so `--format sql` writes `NULL` and a `string`
+  struct field reading it becomes `*string`.
 - `ErrNoColumns` is exported, so a caller can tell the one record fence a path can
   answer from the rest.
 - An error names a spelling that runs: a layout is named single-quoted and free of

README.md

@@ -798,7 +798,9 @@ App developers writing tests and fixtures, in Go and at a shell:
   library's own advice reachable: the error for an object holding only a format
   names `"…"`, and that spelling has to work where it is printed. An argument or struct
   tag of one reference alone, `{/users}`, is refused naming the path `users`: both
-  render the same text, and only the path names a record. `IsTemplate` exports the
+  render the same text, and only the path names a record. A folder-relative `{.name}`
+  or `{..name}` is refused naming `{/name}`, since an inline template sits in no
+  folder. `IsTemplate` exports the
   rule, so the CLI, struct tags and any other caller read one.
 - **An inline template skips the cycle fence.** `New` proves the loaded tree
   acyclic, an inline node is a finite tree of its own, and nothing in the tree can

cmd/fejkdata/main_test.go

@@ -621,3 +621,21 @@ func TestRunNumbersFollowTheShell(t *testing.T) {
 		t.Errorf("run(--seed 007 --repeat +3) = %d, %q, stderr %q; want the same as --seed 7 --repeat 3 %q", code, got, errb, want)
 	}
 }
+
+// TestRunRecordOfAFieldlessPath pins the way out of asking a category of one value
+// for columns: the record to write, and the quoting a shell needs to take it. The
+// argument is well-formed and only the data cannot serve it, so the code is 1.
+func TestRunRecordOfAFieldlessPath(t *testing.T) {
+	code, out, errb := runOut("--format", "csv", "sv_SE.personnummer")
+	if code != 1 {
+		t.Fatalf("run(--format csv sv_SE.personnummer) = %d, want 1", code)
+	}
+	for _, want := range []string{`{"format":"","personnummer":"{/sv_SE.personnummer}"}`, "single quotes"} {
+		if !strings.Contains(errb, want) {
+			t.Errorf("stderr = %q, want it to name %s", errb, want)
+		}
+	}
+	if out != "" {
+		t.Errorf("stdout = %q, want nothing", out)
+	}
+}