cappdutymas

### 1) Overview
 The `cappdutymas` (Company Applicable Duty Master) table serves as a mapping or relationship table within the ERP's taxation module. It defines which specific duty codes (`app_duty_code`) are applicable or associated with a primary duty code (`duty_code`) for a given company. This is typically used to handle compound taxes or to group related duties (e.g., associating an Education Cess with a Basic Excise Duty).
 
 ### 2) Column Dictionary
 
 | Column | Type | Nullable | Meaning | Allowed Values | SQL Usage |
 | :--- | :--- | :--- | :--- | :--- | :--- |
 | **compcode** | string | No | Unique identifier for the company/legal entity. | e.g., "DAS", "PDS" | `WHERE compcode = 'DAS'` |
 | **duty_code** | integer | No | The primary duty/tax code identifier. | Links to `cdutymas` | `JOIN cdutymas ON ...` |
 | **app_duty_code** | integer | No | The secondary or applicable duty code linked to the primary `duty_code`. | Links to `cdutymas` | `JOIN cdutymas AS app ON ...` |
 | **index** | integer | No | Physical row identifier (Primary Key). | | Internal use only |
 
 ### 3) Relationships & Join Map
 
 The table acts as a bridge between various tax masters and transaction-level tax applications.
 
 #### Primary Tax Master Joins (Likely)
 * **dbo.cdutymas**: Join on `duty_code` and `compcode` to retrieve the name and properties of the primary duty.
 * **dbo.cdutymas (Alias: Applicable)**: Join on `app_duty_code` and `compcode` to retrieve details of the associated sub-duty.
 * **dbo.dutymas**: Alternative tax master join on `duty_code`.
 
 #### Module Parity
 * **dbo.appdutymas**: Identical structure; likely used in a different functional module (e.g., Procurement vs. Sales).
 * **dbo.saleappdutymas**: Identical structure; specifically used for Sales-related tax mappings.
 
 #### Transactional Context (Indirect via duty_code)
 * **dbo.invtax**: Joins on `duty_code` to see which mapped duties should be calculated for an invoice.
 * **dbo.potax**: Joins on `duty_code` for Purchase Order tax calculations.
 * **dbo.srnduty**: Joins on `duty_code` for Sales Return tax adjustments.
 
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