schedulehdr

### 1) Overview
 The `schedulehdr` table serves as the header-level record for supplier delivery schedules within the ERP system. It manages the metadata for procurement timing, linking specific Purchase Orders (`pono`) to supplier-specific delivery timelines (`schdate`). It supports version control through amendment tracking (`amendno`, `POAmndNo`) and status management via authorization flags.
 
 ### 2) Column Dictionary
 
 | Column | Type | Nullable | Meaning | Allowed Values | SQL Usage |
 | :--- | :--- | :--- | :--- | :--- | :--- |
 | **index** | integer | NO | Primary Key | | Internal row identifier. |
 | **compcode** | string | NO | Company Code | e.g., "DAS" | Primary filter for all queries. |
 | **schno** | integer | NO | Schedule Number | | Unique identifier for a specific schedule record. |
 | **schdate** | datetime | NO | Schedule Date | | Defines the month/period the schedule applies to. |
 | **pono** | integer | NO | Purchase Order No | | Links to the base Purchase Order. |
 | **podate** | datetime | YES | PO Date | | The date the source PO was issued. |
 | **supcode** | string | NO | Supplier Code | e.g., "TIMIL", "VSSL" | Joins to `suppmas` or `cust`. |
 | **type** | string | NO | Schedule Category | **R**: Raw Material<br>**I**: Intermediate/Semi-Finish<br>**G**: General | Used to determine which detail tables (Items vs RM) to join. |
 | **remarks** | string | YES | Header Remarks | | User-defined notes. |
 | **amendno** | string | YES | Schedule Amendment No | | Tracks revisions to the schedule. |
 | **amenddate** | string | YES | Schedule Amendment Date | | Date of the specific revision. |
 | **POAmndNo** | string | YES | PO Amendment Reference | | Links to a specific revision of the source PO. |
 | **POAmnddate** | string | YES | PO Amendment Date | | Date of the PO revision. |
 | **Auth_Flag** | string | YES | Authorization Status | **Y**: Authorized<br>**N**: Draft | Controls visibility in procurement reports. |
 | **Auth_By** | string | YES | Authorizing User | | User ID of the person who approved the schedule. |
 
 ### 3) Relationships & Join Map
 
 The `schedulehdr` table acts as a central hub for supply chain planning, connecting suppliers, orders, and detailed item schedules.
 
 #### Primary Joins (Confirmed via SCHEMA_MAP)
 * **scheduledtl**: Join on `compcode` and `schno`. This retrieves the specific items and quantities associated with this schedule header.
 * **suppmas**: Join on `compcode` and `supcode`. Retrieves supplier contact and master data.
 * **schedulehdramnd**: Join on `compcode`, `schno`, and `amendno`. Used for comparing historical schedule versions.
 
 #### Likely Logic Joins (Contextual via REFERENCE_JSON)
 * **rmpotab / cpohdr**: Join on `compcode` and `pono`. Links the schedule to the financial Purchase Order contract.
 * **fghdr (Finish Goods)**: Joins on `compcode` and `supcode` (matching against `fghdr.supcode`) when `type = 'I'`.
 * **rmincoming (RM Receipts)**: Joins on `compcode` and `supcode` (matching against `rmincoming.supcode`) when `type = 'R'`.
 * **incomconitem (Consumable Receipts)**: Joins on `compcode` and `supcode` (matching against `incomconitem.supcode`) when `type = 'G'`.
 * **debithdr**: Joins on `compcode` and `supcode` (matching against `debithdr.custcode`) to track schedule deductions or returns.