potype

### 1. Overview
 The `potype` table serves as a reference master for Purchase Order (PO) categories within the system. It defines specific types of purchase documents (e.g., "CS" for Customer Service/Contract Sale or "CP" for Central Purchase) mapped against specific company codes. This table is primarily used to validate or categorize headers in the purchasing and procurement modules.
 
 ### 2. Column Dictionary
 
 | Column | Type | Nullable | Meaning | Allowed Values | SQL Usage |
 | :--- | :--- | :--- | :--- | :--- | :--- |
 | **index** | integer | No | Primary key identifier for the record. | | Primary Key |
 | **compcode** | string | No | The unique identifier for the company/branch. | e.g., "DAS", "PDS" | Join, Filter |
 | **type** | string | No | The alphanumeric code representing the PO Type. | e.g., "CS", "CP" | Join, Group By |
 
 ### 3. Relationships & Join Map
 
 The `potype` table acts as a validation source for Purchase Order headers. Joins should be restricted to tables containing both company identifiers and PO type classifications.
 
 #### Primary Joins (Authoritative)
 * **dbo.cpohdr** (`compcode`, `type`): Joins to the Purchase Order Header to provide type-based descriptions or filtering for active POs.
 * **dbo.cpohdramnd** (`compcode`, `type`): Joins to the Purchase Order Amendment history to track changes within specific PO categories.
 * **dbo.cpotemphdr** (`compcode`, `type`): Joins to the temporary/draft Purchase Order storage during the creation process.
 
 #### Likely/Inferred Joins
 * **dbo.company** (`compcode`): Joins to retrieve full company metadata.
 * **dbo.pohdr** (`compcode`): While `pohdr` lacks a direct `type` column in the schema map, it is functionally related to PO types via the company context.
 * **dbo.cust** (`compcode`, `type`): Likely used to filter customers based on the types of POs they are eligible to receive or issue.