> For the complete documentation index, see [llms.txt](https://help.auxalia.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.auxalia.com/plant-tools/plantexpresstools/how-to-use/off-page-connector-manager/usage/additional-use-cases/handling-of-calculations.md).
# Handling of Calculations
The chapter describes how the OPC Manager handles PlantExpressTools calculations when values are copied when connecting OPCs.
### Calculation
For this example we have a calculation which extracts the first 2 digits of the 'Spec' property and stores it in 'Design Pressure'.
### Tree Settings
Since the Design Pressure is calculated we wouldn't need to add this property to the Mapping Grid. However, for the purpose of this documentation we add it to later see what is happening. Since it is calculated, we deactivate the checkbox under 'Check for Inconsistency'. We also set the 'Mapping/Propagation Direction' to None.
### Connecting
As before, we connect.
We get the inconsistencies and we see the Design Pressure which was calculated already (before made the connection) in drawing PID 001.
We copy the values.
Everything is green and the calculation of the 'Design Pressure' in drawing PID 002 was also updated. This was not done by copying, but by actually running/updating the calculation.
If we now open the drawing and select the Line Segment we see, that here as well, that the calculated property was updated.
