Pattern B — EventSubscriber Event Map

Use this map when the posting codeunit does NOT call TransferFields from the source to the target. You must:

1. Extend the source table with a TableExt (same Field ID as on target).
2. Extend the target table with a TableExt (same Field ID).
3. Create a dedicated EventSubscriber codeunit for the module — one codeunit per posting chain, not one per field.

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How to confirm Pattern B applies

Open the BC posting codeunit. Search for TransferFields between the source record variable and the target insert variable. If TransferFields is absent, you need a subscriber using one of the events below.

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Event Map

Source Table	Source ID	Target Table	Target ID	Posting Codeunit	Codeunit ID	Event Name
Item Journal Line	83	Item Ledger Entry	32	Item Jnl.-Post Line	22	OnBeforeInsertItemLedgEntry
Item Journal Line	83	Capacity Ledger Entry	5832	Item Jnl.-Post Line	22	OnBeforeInsertCapLedgEntry
Item Journal Line	83	Value Entry	5802	Item Jnl.-Post Line	22	OnBeforeInsertValueEntry
Gen. Journal Line	81	Cust. Ledger Entry	21	(Table event)	Table 21	OnAfterCopyCustLedgerEntryFromGenJnlLine
Gen. Journal Line	81	Vendor Ledger Entry	25	(Table event)	Table 25	OnAfterCopyVendLedgerEntryFromGenJnlLine
Gen. Journal Line	81	G/L Entry	17	Gen. Jnl.-Post Line	12	OnAfterInsertGLEntry
Resource Journal Line	207	Res. Ledger Entry	203	Res. Jnl.-Post Line	212	OnAfterInsertResLedgEntry
Cash Flow Worksheet Line	841	Cash Flow Forecast Entry	840	Cash Flow Wksh.-Register Line	843	OnAfterCreateForecastEntry
Routing Line	99000758	Prod. Order Routing Line	5409	Calculate Prod. Order	99000773	OnAfterTransferRoutingLine
Assembly Header	900	Posted Assembly Header	910	Assembly-Post	900	OnAfterPostAssemblyHeader
Assembly Line	901	Posted Assembly Line	911	Assembly-Post	900	OnAfterPostAssemblyLine
Warehouse Receipt Line	7317	Posted Whse. Receipt Line	7319	Whse.-Post Receipt	5760	OnAfterPostWhseRcptLine
Warehouse Shipment Line	7321	Posted Whse. Shipment Line	7323	Whse.-Post Shipment	5763	OnAfterPostWhseShptLine
Payment Order (ES)	7000006	Cartera Doc.	7000001	Bill Groups-Post (ES)	7000000	OnAfterInsertPayableDocs

Note: The Payment Order → Cartera Doc. entry applies only to Spanish Cartera localization. Omit it if the extension targets a non-ES market.

Note: Res. Ledger Entry — the OnAfterInsertResLedgEntry event is raised inside Codeunit 212 ("Res. Jnl.-Post Line"). If that event is not accessible in your BC version, use OnBeforeInsertResLedgEntry or a local procedure integration event exposed by the posting codeunit.

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Subscriber Codeunit Structure (per module)

One dedicated codeunit per module/posting chain. Do not mix subscribers from different posting chains in the same codeunit.

codeunit 50XXX "Ev[PostingChain][ModuleName]"
{
    // Subscribes to ONE posting chain (e.g., Item Journal Line posting)
    // All fields for this module from that chain go here.

    [EventSubscriber(ObjectType::Codeunit, Codeunit::"Item Jnl.-Post Line",
        'OnBeforeInsertItemLedgEntry', '', false, false)]
    local procedure OnBeforeInsertItemLedgEntry(var ItemLedgerEntry: Record "Item Ledger Entry";
        ItemJournalLine: Record "Item Journal Line")
    begin
        ItemLedgerEntry.MyCustomField := ItemJournalLine.MyCustomField;
    end;

    [EventSubscriber(ObjectType::Codeunit, Codeunit::"Item Jnl.-Post Line",
        'OnBeforeInsertCapLedgEntry', '', false, false)]
    local procedure OnBeforeInsertCapLedgEntry(var CapacityLedgerEntry: Record "Capacity Ledger Entry";
        ItemJournalLine: Record "Item Journal Line")
    begin
        CapacityLedgerEntry.MyCustomField := ItemJournalLine.MyCustomField;
    end;
}

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Field ID Alignment Rule

Always use the same Field ID on both the source TableExt and the target TableExt. This makes future migration to Pattern A trivial if BC later exposes a TransferFields path, and keeps IDs auditable across the extension.

// Source: Item Journal Line TableExt
field(50100; MyCustomField; Text[50]) { ... }

// Target: Item Ledger Entry TableExt — same ID
field(50100; MyCustomField; Text[50]) { ... }

// Target: Capacity Ledger Entry TableExt — same ID
field(50100; MyCustomField; Text[50]) { ... }