The core model

The universal column envelope, the three ledger patterns and the polymorphic party — the shape that repeats across all 448 entities.

The data model in brief is what this stage points at — read it in full. It covers three things every module page and system design assumes you already know:

• The universal column envelope every entity inherits, and why primary keys are strings rather than surrogate integers.
• The three ledger patterns (GL Entry, Stock Ledger Entry, Payment Ledger Entry) that make append-only, reversal-not-edit the default posture for anything carrying financial or quantity truth.
• The polymorphic party pattern — how party_type + party, and reference_doctype + reference_name, let one field point at different doctypes depending on context.

It also draws the Order to Cash, Procure to Pay and Plan to Produce transaction chains — the paths most documents in this system travel.

Why this stage exists on its own

Stage 3 walks module pages; those pages assume you already recognise a ledger pattern or a transaction-chain step on sight. If a module page’s diagram is confusing, the fix is almost always here, not there.

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