cdutymas

### 1) Overview
 The `cdutymas` table serves as the **Duty and Tax Master** within the ERP system. It defines the various types of taxes (GST, Excise, VAT), charges (Freight, Packing, Courier), and adjustments (Round-off) applicable to purchase and service transactions. It provides a centralized configuration for tax rates, accounting ledger mappings, and HSN codes, specifically for the "Consumption" or "Purchase/Service" side of the business (distinguished from `saledutymas`).
 
 ### 2) Column Dictionary
 
 | Column | Type | Nullable | Meaning | Allowed Values | SQL Usage |
 | :--- | :--- | :--- | :--- | :--- | :--- |
 | **index** | integer | NO | Primary internal identifier. | | PK |
 | **compcode** | string | NO | Unique Company identifier. | e.g., 'DAS', 'PDS' | Join Key |
 | **duty_code** | integer | NO | Unique identifier for the specific duty/charge. | 0-99 (e.g., 51=SGST) | Join Key |
 | **duty_name** | string | YES | Descriptive name of the duty or charge. | SGST, CGST, IGST, FREIGHT | Display |
 | **nature** | string | YES | Arithmetic impact on the total value. | '+', '-' | Calculation logic |
 | **username** | string | YES | User who created or last modified the entry. | admin, system, ppc | Audit |
 | **sequence** | integer | YES | Sorting order for display in forms/reports. | 0, 1, 2, ... | ORDER BY |
 | **roff** | string | YES | Round-off flag indicator. | 'Y', 'N', NULL | Logic |
 | **type** | string | YES | Internal classification code. | | Likely Filter |
 | **duty_type** | string | YES | Sub-categorization of the duty. | | Likely Filter |
 | **lock_flag** | string | YES | Prevents modification if locked. | 'Y', 'N' | Validation |
 | **HSN** | string | YES | Harmonized System Nomenclature code for taxation. | | Reporting |
 | **taxrate** | number | YES | Default percentage rate for the duty. | | Calculation |
 | **alias** | string | YES | Short name or alternate reference. | | Display |
 | **ledgercode** | number | YES | Link to the Financial Accounting Ledger. | | GL Integration |
 
 ### 3) Relationships & Join Map
 
 The `cdutymas` table is a critical reference for mapping duty codes to transaction details. It is primarily joined via `compcode` and `duty_code`.
 
 #### Primary Joins (SCHEMA_MAP Verified)
 * **dbo.csrnduty** (`duty_code`, `compcode`): Maps detailed tax amounts for Consumable Store Receipt Notes (CSRN).
 * **dbo.cmrrduty** (`duty_code`, `compcode`): Maps tax details for Consumable Material Receipt Returns.
 * **dbo.appdutymas** (`duty_code`, `compcode`): Linkage for "Applied" duties in procurement workflows.
 * **dbo.cappdutymas** (`duty_code`, `compcode`): Linkage for "Consumable Applied" duties.
 * **dbo.custtax** (`duty_code`, `compcode`): Customer-specific tax configurations.
 * **dbo.vendtax** (`duty_code`, `compcode`): Vendor-specific tax configurations.
 
 #### Contextual Joins (REFERENCE_JSON Verified)
 * **dbo.servicedtl** (`dutycode` = `duty_code`): Used in GST Register procedures to fetch HSN and Duty Names for service-related invoices.