# Implementation Differences and Porting Policy

## Policy

Neither `URCtrl` nor `CobottaCtrl` is the unilateral standard. The objective is a common collaborative-robot interface.

Well-designed APIs established in the UR implementation may therefore be incorporated into `cobotta_ctrl`.

## Variable Management

UR lacks RC8 P registers, so it uses `RobotVarManager`.

In the future, COBOTTA may also distinguish physical robot-internal variables from locally managed variables more explicitly.

## Status Monitoring

The UR implementation aggregates robot mode, safety mode, status bits, and Dashboard information in `state()`.

This is useful for the common interface, so the COBOTTA `task_state` / `state()` functions are candidates for alignment.

## Error Information

Because detailed error text is unavailable through UR RTDE, error information is synthesized from status data.

COBOTTA can retrieve RC8 error information, but the higher-level interface should ideally standardize on `get_current_error_info()`.

## No-Ops Versus Unsupported Features

`take_arm()` and `give_arm()` are no-ops on UR.

Dedicated hands and PacScript, however, are explicitly unsupported.

The common interface distinguishes no-op functions from unsupported ones.

## BL774 / SPring-8 Integration

The purpose of the common interface is to integrate robots into experimental systems.

The API therefore prioritizes:

- Concise calls  
- Readable status  
- Diagnostic information on failure  
- Easy deployment as a server  
- Easy integration into instrument-control sequences  

Exposing every manufacturer-specific API is not the objective.