diff --git a/lib/bind9/api b/lib/bind9/api
index 2a59ac929c..e34aa945db 100644
--- a/lib/bind9/api
+++ b/lib/bind9/api
@@ -1,3 +1,8 @@
+# LIBINTERFACE ranges
+# 9.6: 50-59, 110-119
+# 9.7: 60-79
+# 9.8: 80-89
+# 9.9: 90-109
 LIBINTERFACE = 90
 LIBREVISION = 2
 LIBAGE = 0
diff --git a/lib/dns/api b/lib/dns/api
index f7fd555777..332a0c5447 100644
--- a/lib/dns/api
+++ b/lib/dns/api
@@ -1,3 +1,8 @@
+# LIBINTERFACE ranges
+# 9.6: 50-59, 110-119
+# 9.7: 60-79
+# 9.8: 80-89
+# 9.9: 90-109
 LIBINTERFACE = 93
 LIBREVISION = 0
 LIBAGE = 0
diff --git a/lib/irs/api b/lib/irs/api
index 3d2fa6efd1..a45a6bffef 100644
--- a/lib/irs/api
+++ b/lib/irs/api
@@ -1,3 +1,8 @@
+# LIBINTERFACE ranges
+# 9.6: 50-59, 110-119
+# 9.7: 60-79
+# 9.8: 80-89
+# 9.9: 90-109
 LIBINTERFACE = 90
 LIBREVISION = 0
 LIBAGE = 0
diff --git a/lib/isc/api b/lib/isc/api
index 580ddcfd7a..8a3bcf60bd 100644
--- a/lib/isc/api
+++ b/lib/isc/api
@@ -1,3 +1,8 @@
+# LIBINTERFACE ranges
+# 9.6: 50-59, 110-119
+# 9.7: 60-79
+# 9.8: 80-89
+# 9.9: 90-109
 LIBINTERFACE = 91
 LIBREVISION = 0
 LIBAGE = 1
diff --git a/lib/isccc/api b/lib/isccc/api
index 3d2fa6efd1..a45a6bffef 100644
--- a/lib/isccc/api
+++ b/lib/isccc/api
@@ -1,3 +1,8 @@
+# LIBINTERFACE ranges
+# 9.6: 50-59, 110-119
+# 9.7: 60-79
+# 9.8: 80-89
+# 9.9: 90-109
 LIBINTERFACE = 90
 LIBREVISION = 0
 LIBAGE = 0
diff --git a/lib/isccfg/api b/lib/isccfg/api
index 6404d993e5..59e4f66cb6 100644
--- a/lib/isccfg/api
+++ b/lib/isccfg/api
@@ -1,3 +1,8 @@
+# LIBINTERFACE ranges
+# 9.6: 50-59, 110-119
+# 9.7: 60-79
+# 9.8: 80-89
+# 9.9: 90-109
 LIBINTERFACE = 90
 LIBREVISION = 1
 LIBAGE = 0
diff --git a/lib/lwres/api b/lib/lwres/api
index 3d2fa6efd1..a45a6bffef 100644
--- a/lib/lwres/api
+++ b/lib/lwres/api
@@ -1,3 +1,8 @@
+# LIBINTERFACE ranges
+# 9.6: 50-59, 110-119
+# 9.7: 60-79
+# 9.8: 80-89
+# 9.9: 90-109
 LIBINTERFACE = 90
 LIBREVISION = 0
 LIBAGE = 0