schedulehdramnd

### 1. Overview
 The `schedulehdramnd` table serves as the **Amendment History Header** for procurement or production schedules. It stores version-controlled snapshots of schedule headers, tracking changes made to supplier assignments, dates, and associations with Purchase Orders. Every time a schedule is revised, a new entry is created here with an incremented `amendno`.
 
 ### 2. Column Dictionary
 
 | Column | Type | Nullable | Meaning | Allowed Values | SQL Usage |
 | :--- | :--- | :--- | :--- | :--- | :--- |
 | **index** | integer | No | Primary Key | | Surrogate Key |
 | **compcode** | string | No | Company Identifier | e.g., "DAS" | Join Key |
 | **schno** | integer | No | Schedule Number | | Join Key |
 | **schdate** | datetime | Yes | Original Schedule Date | | Filtering |
 | **pono** | integer | Yes | Purchase Order Number | | Join Key |
 | **podate** | datetime | Yes | Purchase Order Date | | Reporting |
 | **supcode** | string | Yes | Supplier/Vendor Code | | Join Key |
 | **type** | string | Yes | Schedule Category | **R**: Raw Material<br>**I**: Item/Finished Good<br>**G**: General | Conditional Joins |
 | **remarks** | string | Yes | Revision comments or notes | | Documentation |
 | **amendno** | integer | No | Amendment Sequence Number | 0 = Original, 1+ = Revisions | Versioning |
 | **amenddate** | datetime | Yes | Date the amendment was created | | Audit/Tracking |
 | **POAmndNo** | string | Yes | Linked PO Amendment Number | | Cross-reference |
 | **POAmnddate** | string | Yes | Linked PO Amendment Date | | Cross-reference |
 
 ### 3. Relationships & Join Map
 
 #### Logical Primary Key
 The logical uniqueness is defined by the combination of `compcode`, `schno`, and `amendno`.
 
 #### Authoritative Joins (via SCHEMA_MAP)
 * **scheduledtlamnd**: This is the primary child table containing line-item details for the specific amendment.
  * `JOIN dbo.scheduledtlamnd ON schedulehdramnd.schno = scheduledtlamnd.schno AND schedulehdramnd.compcode = scheduledtlamnd.compcode AND schedulehdramnd.amendno = scheduledtlamnd.amendno`
 * **suppmas**: To retrieve supplier names and contact details.
  * `JOIN dbo.suppmas ON schedulehdramnd.supcode = suppmas.supcode AND schedulehdramnd.compcode = suppmas.compcode`
 * **schedulehdr**: To compare an amendment against the current "active" or "original" schedule.
  * `JOIN dbo.schedulehdr ON schedulehdramnd.schno = schedulehdr.schno AND schedulehdramnd.compcode = schedulehdr.compcode`
 * **cpohdr / pohdr**: To link the schedule to its parent Purchase Order.
  * `JOIN dbo.cpohdr ON schedulehdramnd.pono = cpohdr.pono AND schedulehdramnd.compcode = cpohdr.compcode`
 
 #### Conditional Joins (Likely)
 Based on the `type` column and `Sup_amend_detail` logic:
 * If `type = 'I'`, join to **itemmas** on `itemcode`.
 * If `type = 'R'`, join to **rmmas** on `rmcode`.
 * If `type = 'G'`, join to **citemmas** on `citmcode`.