diff --git a/README.md b/README.md
index b7ad560..d60edea 100644
--- a/README.md
+++ b/README.md
@@ -251,6 +251,11 @@ the side gives the direction.
 - `instrument` on an event: the payment method (a `setup.instruments`
   label) the entry was paid with. Neither `parties` nor `instrument` on a
   reversal, which takes its original's, nor on a command.
+- `older = true` on an entry (`lines`): the entry as an earlier version
+  could write it, which this version's commands refuse: a line by hand
+  on a receivables or payables account, where only an invoice, a bill or
+  their payments post now (rules.md B-38, the control guard). Books that
+  hold one must still read right, so the books take it as replay does.
 - `close = { start, to, rounding? }` as an event: closes the period from
   `start` through the event's `date` (rules.md B-11, B-13), `to`
   `"members"` (split by share, in the order listed) or
diff --git a/examples/1099-money-from-a-payee-is-netted-only-as-a-refund.toml b/examples/1099-money-from-a-payee-is-netted-only-as-a-refund.toml
index c084509..994db64 100644
--- a/examples/1099-money-from-a-payee-is-netted-only-as-a-refund.toml
+++ b/examples/1099-money-from-a-payee-is-netted-only-as-a-refund.toml
@@ -63,6 +63,7 @@ lines = [
 [[events]]
 date = "2026-03-01"
 description = "Dana Studio pays the company's invoice"
+older = true
 payee = "Dana Studio"
 lines = [
   { account = "1000", side = "debit", amount = "450.00" },
diff --git a/examples/p3-party-signs-and-reversals.toml b/examples/p3-party-signs-and-reversals.toml
index 43c35f2..889a21c 100644
--- a/examples/p3-party-signs-and-reversals.toml
+++ b/examples/p3-party-signs-and-reversals.toml
@@ -176,6 +176,7 @@ lines = [
 [[events]]
 date = "2026-10-20"
 description = "Bill"
+older = true
 parties = [{ party = "Northwind Filings" }]
 lines = [
   { account = "6000", side = "debit", amount = "80.00" },
@@ -192,6 +193,7 @@ reverses = 7
 [[events]]
 date = "2026-10-20"
 description = "Invoice"
+older = true
 parties = [{ party = "Riley Chen" }]
 lines = [
   { account = "1200", side = "debit", amount = "120.00" },
diff --git a/examples/projects-invoice-and-bill-lines-count-by-project.toml b/examples/projects-invoice-and-bill-lines-count-by-project.toml
index 386d961..dfccb7c 100644
--- a/examples/projects-invoice-and-bill-lines-count-by-project.toml
+++ b/examples/projects-invoice-and-bill-lines-count-by-project.toml
@@ -95,6 +95,7 @@ bill = { vendor = "Dana Illustration", lines = [
 [[events]]
 date = "2026-03-20"
 description = "Cedar pays invoice 1"
+older = true
 lines = [
   { account = "1000", side = "debit", amount = "3800.00" },
   { account = "1200", side = "credit", amount = "3800.00" },
@@ -103,6 +104,7 @@ lines = [
 [[events]]
 date = "2026-03-30"
 description = "Pay Dana's bill"
+older = true
 payee = "Dana Illustration"
 lines = [
   { account = "2000", side = "debit", amount = "1250.00" },
diff --git a/examples/projects-net-is-its-tagged-lines.toml b/examples/projects-net-is-its-tagged-lines.toml
index fb1c60b..d770b0c 100644
--- a/examples/projects-net-is-its-tagged-lines.toml
+++ b/examples/projects-net-is-its-tagged-lines.toml
@@ -33,7 +33,7 @@ code = "1000"
 name = "Cash"
 type = "asset"
 [[setup.accounts]]
-code = "1200"
+code = "1500"
 name = "Equipment"
 type = "asset"
 [[setup.accounts]]
@@ -93,7 +93,7 @@ lines = [
 date = "2026-03-05"
 description = "Test devices for Beta"
 lines = [
-  { account = "1200", side = "debit", amount = "900.00", project = "Beta" },
+  { account = "1500", side = "debit", amount = "900.00", project = "Beta" },
   { account = "1000", side = "credit", amount = "900.00" },
 ]
 [[events]]