diff --git a/common/proto/accounting.proto b/common/proto/accounting.proto
index 55df4b19..bc476a65 100644
--- a/common/proto/accounting.proto
+++ b/common/proto/accounting.proto
@@ -1,7 +1,7 @@
 syntax = "proto3";
 package komp_ac.accounting;
 
-import "exchange_rates.proto";
+import "common.proto";
 
 // Mutable informational journals. A journal may contain only debits, only
 // credits, or any non-zero balance. Balance is reported but never enforced.
@@ -170,9 +170,9 @@ message JournalLineInput {
   string account = 2;
   string amount = 3;
   string description = 4;
-  // Empty uses the profile provider's previous publication. Set this per line when the
-  // accountant needs a different rule, a saved custom rate, or a one-off rate.
-  optional komp_ac.exchange_rates.ExchangeRateSelection exchange_rate_selection = 5;
+  // Omit to use the selected conversion module's posting policy.
+  // Explicit options are interpreted only by their named module.
+  optional komp_ac.common.CurrencyConversionOptions conversion_options = 5;
 }
 
 message CloseJournalRequest {
@@ -325,6 +325,7 @@ message JournalLine {
   string original_amount = 16;
   string original_currency = 17;
   int64 conversion_evidence_id = 18;
+  int64 conversion_table_definition_id = 19;
 }
 
 message Journal {
diff --git a/common/proto/common.proto b/common/proto/common.proto
index 073e01c5..cf40321e 100644
--- a/common/proto/common.proto
+++ b/common/proto/common.proto
@@ -9,3 +9,9 @@ message CountResponse {
 message PositionRequest {
   int64 position = 1;
 }
+
+// Options interpreted only by the named currency-conversion module.
+message CurrencyConversionOptions {
+  string module_id = 1;
+  string options_json = 2;
+}
diff --git a/common/proto/tables_data.proto b/common/proto/tables_data.proto
index 49919fda..bd8c6613 100644
--- a/common/proto/tables_data.proto
+++ b/common/proto/tables_data.proto
@@ -3,7 +3,6 @@ syntax = "proto3";
 package komp_ac.tables_data;
 
 import "common.proto";
-import "exchange_rates.proto";
 import "google/protobuf/struct.proto";
 
 // Read and write row data for user-defined tables inside profiles (schemas).
@@ -166,7 +165,7 @@ map<string, google.protobuf.Value> data = 3;
 
 message PostAccountingTableDataRequest {
   PostTableDataRequest row = 1;
-  komp_ac.exchange_rates.ExchangeRateSelection exchange_rate_selection = 2;
+  komp_ac.common.CurrencyConversionOptions conversion_options = 2;
 }
 
 // Insert response.
@@ -272,7 +271,7 @@ message PutTableDataRequest {
 
 message PutAccountingTableDataRequest {
   PutTableDataRequest update = 1;
-  komp_ac.exchange_rates.ExchangeRateSelection exchange_rate_selection = 2;
+  komp_ac.common.CurrencyConversionOptions conversion_options = 2;
   bool confirmed = 3;
   repeated string expected_affected_profiles = 4;
 }
diff --git a/common/src/proto/descriptor.bin b/common/src/proto/descriptor.bin
index 001cb632..b4a81cb0 100644
Binary files a/common/src/proto/descriptor.bin and b/common/src/proto/descriptor.bin differ
diff --git a/common/src/proto/komp_ac.accounting.rs b/common/src/proto/komp_ac.accounting.rs
index ea5f7d50..4707807e 100644
--- a/common/src/proto/komp_ac.accounting.rs
+++ b/common/src/proto/komp_ac.accounting.rs
@@ -72,11 +72,11 @@ pub struct JournalLineInput {
     pub amount: ::prost::alloc::string::String,
     #[prost(string, tag = "4")]
     pub description: ::prost::alloc::string::String,
-    /// Empty uses the profile provider's previous publication. Set this per line when the
-    /// accountant needs a different rule, a saved custom rate, or a one-off rate.
+    /// Omit to use the selected conversion module's posting policy.
+    /// Explicit options are interpreted only by their named module.
     #[prost(message, optional, tag = "5")]
-    pub exchange_rate_selection: ::core::option::Option<
-        super::exchange_rates::ExchangeRateSelection,
+    pub conversion_options: ::core::option::Option<
+        super::common::CurrencyConversionOptions,
     >,
 }
 #[derive(serde::Serialize, serde::Deserialize)]
@@ -314,6 +314,8 @@ pub struct JournalLine {
     pub original_currency: ::prost::alloc::string::String,
     #[prost(int64, tag = "18")]
     pub conversion_evidence_id: i64,
+    #[prost(int64, tag = "19")]
+    pub conversion_table_definition_id: i64,
 }
 #[derive(serde::Serialize, serde::Deserialize)]
 #[derive(Clone, PartialEq, ::prost::Message)]
diff --git a/common/src/proto/komp_ac.common.rs b/common/src/proto/komp_ac.common.rs
index 211fa638..f037304d 100644
--- a/common/src/proto/komp_ac.common.rs
+++ b/common/src/proto/komp_ac.common.rs
@@ -14,3 +14,12 @@ pub struct PositionRequest {
     #[prost(int64, tag = "1")]
     pub position: i64,
 }
+/// Options interpreted only by the named currency-conversion module.
+#[derive(serde::Serialize, serde::Deserialize)]
+#[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
+pub struct CurrencyConversionOptions {
+    #[prost(string, tag = "1")]
+    pub module_id: ::prost::alloc::string::String,
+    #[prost(string, tag = "2")]
+    pub options_json: ::prost::alloc::string::String,
+}
diff --git a/common/src/proto/komp_ac.tables_data.rs b/common/src/proto/komp_ac.tables_data.rs
index 4ecd6908..6a190133 100644
--- a/common/src/proto/komp_ac.tables_data.rs
+++ b/common/src/proto/komp_ac.tables_data.rs
@@ -54,8 +54,8 @@ pub struct PostAccountingTableDataRequest {
     #[prost(message, optional, tag = "1")]
     pub row: ::core::option::Option<PostTableDataRequest>,
     #[prost(message, optional, tag = "2")]
-    pub exchange_rate_selection: ::core::option::Option<
-        super::exchange_rates::ExchangeRateSelection,
+    pub conversion_options: ::core::option::Option<
+        super::common::CurrencyConversionOptions,
     >,
 }
 /// Insert response.
@@ -187,8 +187,8 @@ pub struct PutAccountingTableDataRequest {
     #[prost(message, optional, tag = "1")]
     pub update: ::core::option::Option<PutTableDataRequest>,
     #[prost(message, optional, tag = "2")]
-    pub exchange_rate_selection: ::core::option::Option<
-        super::exchange_rates::ExchangeRateSelection,
+    pub conversion_options: ::core::option::Option<
+        super::common::CurrencyConversionOptions,
     >,
     #[prost(bool, tag = "3")]
     pub confirmed: bool,
diff --git a/server b/server
index 1da33d65..f00542d0 160000
--- a/server
+++ b/server
@@ -1 +1 @@
-Subproject commit 1da33d65622004d0005b672a7b67b2f69d7c9492
+Subproject commit f00542d009fdb32b1f9c1426ec0522cfe52ae28e