diff --git a/go/seatdef/seatdef.go b/go/seatdef/seatdef.go
index 50f0da4..f1336f3 100644
--- a/go/seatdef/seatdef.go
+++ b/go/seatdef/seatdef.go
@@ -389,8 +389,16 @@ func (d Definition) check() Problems {
 		if !eventName.MatchString(e.Name) {
 			ps = append(ps, Problem{where + ".name", "missing, or not lower-case words joined by dots"})
 		}
-		if e.Subject == "" {
+		// A holder's event is published under the holder's own module subjects, or, when it is kept in a stream of the
+		// holder's own module (its family), under that stream's (buscompose.ModuleStreamSubject).
+		own, stream := "mesh.mod.<holder>.event."+e.Name, "mesh.stream.<holder>.event."+e.Name
+		switch {
+		case e.Subject == "":
 			ps = append(ps, Problem{where + ".subject", "missing"})
+		case e.Subject == stream && e.Family == "":
+			ps = append(ps, Problem{where + ".subject", "a subject of the holder's own stream, and no family names that stream"})
+		case e.Subject != own && e.Subject != stream:
+			ps = append(ps, Problem{where + ".subject", fmt.Sprintf("not %s, nor %s for an event kept in the holder's own stream", own, stream)})
 		}
 	}
 	for i, r := range d.Records {
diff --git a/go/seatdef/seatdef_test.go b/go/seatdef/seatdef_test.go
index 7f27a8f..e51f316 100644
--- a/go/seatdef/seatdef_test.go
+++ b/go/seatdef/seatdef_test.go
@@ -41,6 +41,12 @@ func TestADefinitionIsReadStrictlyNamingWhatIsWrong(t *testing.T) {
 			`"max-age-days":30`, 1), "family.max-age-days: missing, or not 7"},
 		{"a family with a cap of its own", strings.Replace(whole, `"max-age-days":7`, `"max-age-days":7,"max-mib":256`, 1),
 			"max-mib: a field the format does not know"},
+		{"a holder's event on its own stream", strings.Replace(whole, `"family":`, `"holder-events":[{"name":"verdict",`+
+			`"subject":"mesh.stream.<holder>.event.verdict","family":"checker.asks"}],"family":`, 1), ""},
+		{"a holder's event on its own stream with no family", strings.Replace(whole, `"family":`, `"holder-events":[{"name":"verdict",`+
+			`"subject":"mesh.stream.<holder>.event.verdict"}],"family":`, 1), "no family names that stream"},
+		{"a holder's event on a subject of no module", strings.Replace(whole, `"family":`, `"holder-events":[{"name":"verdict",`+
+			`"subject":"mesh.event.verdict"}],"family":`, 1), "holder-events[0].subject: not mesh.mod.<holder>.event.verdict"},
 		{"a verb twice", strings.Replace(listGrain, `]}`, `,{"name":"add"}]}`, 1), `"add" twice`},
 		{"records at the seat list's grain", strings.Replace(listGrain, `"decision":"ADR 1",`,
 			`"decision":"ADR 1","records":[{"name":"asks"}],`, 1), "grain: seat-list holds"},