suptax

### 1) Overview
 The `suptax` table serves as a configuration mapping between suppliers and their applicable tax/duty structures within the SQL Server database. It defines specific tax percentages (`taxpercentage`) for various duty types (`duty_code`) associated with a particular supplier (`supcode`). This table is essential for calculating tax components during procurement processes, such as Purchase Orders or Goods Receipts.
 
 ### 2) Column Dictionary
 
 | Column | Type | Nullable | Meaning | Allowed Values | SQL Usage |
 | :--- | :--- | :--- | :--- | :--- | :--- |
 | **index** | integer | No | Primary Key (Internal) | Auto-incrementing | `WHERE index = 0` |
 | **compcode** | string | No | Company identifier | e.g., "DAS" | `JOIN ... ON a.compcode = b.compcode` |
 | **supcode** | string | No | Supplier unique code | e.g., "BPPL", "RS" | Joins to `suppmas.supcode` |
 | **srno** | integer | No | Sequence number for taxes per supplier | 1, 2, 3... | Sort order for tax calculation |
 | **duty_code** | integer | No | Reference to the tax/duty master | 0, 7, 11, 25, 52 | Joins to `dutymas.duty_code` |
 | **taxpercentage** | number | No | Applicable tax rate/percentage | 0.0 to 100.0 | Used in VAT/GST/Duty calculations |
 | **suptaxflag** | string | No | Type category flag | 'S', 'P' | Likely: 'S' (Service/Sales), 'P' (Purchase) |
 
 ### 3) Relationships & Join Map
 
 Based on the `SCHEMA_MAP`, the following joins are authoritative:
 
 #### Mandatory Joins (Primary)
 * **Supplier Master:** `suptax.supcode` joins to `suppmas.supcode` and `suptax.compcode` joins to `suppmas.compcode`.
 * **Duty Master:** `suptax.duty_code` joins to `dutymas.duty_code` (and `cdutymas.duty_code`) to retrieve the name and nature of the tax.
 
 #### Functional Joins (Procurement & Finance)
 * **Purchase Orders (Header):** `suptax.supcode` joins to `cpohdr.supcode` to default tax rates on new orders.
 * **Raw Material Incoming:** `suptax.supcode` joins to `rmincoming.supcode` for validating tax amounts on bills.
 * **Purchase Billing:** `suptax.supcode` joins to `RM_SF_Purchase_Bill.SupCode` (Likely case-insensitive match).
 
 #### Likely Inference
 * **Tax Grouping:** This table is functionally related to `custtax` (customer-side equivalent), which shares a similar structure for sales-side tax mapping.