Pressure unit: barg and bar_abs instead of bar

[jkisse]

From the naming, it is not really clear whether the unit for pressure refers to absolute or relative pressure. It would be helpful to change the naming to barg (bar gauge) where applicable and use bar_abs where absolute pressure are meant.
As far as I understand, "bar" currently means "barg" but this should be stated in the documentation somewhere.

[jkisse]

It would probably a breaking change, but backward compatibility could be kept with some custom DF modifications, according to a ChatBot:...

import pandas as pd
import warnings

class CustomDataFrame(pd.DataFrame):
    @property
    def _constructor(self):
        return CustomDataFrame

    def __getitem__(self, key):
        if key == 'old_column_name':  # Replace with your old column name
            warnings.warn("The column 'old_column_name' is deprecated, use 'new_column_name' instead.", DeprecationWarning)
            return super().__getitem__('new_column_name')  # Replace with your new column name
        return super().__getitem__(key)

    def __getattr__(self, attr):
        if attr == 'old_column_name':  # Replace with your old column name
            warnings.warn("The column 'old_column_name' is deprecated, use 'new_column_name' instead.", DeprecationWarning)
            return self['new_column_name']  # Replace with your new column name
        return super().__getattr__(attr)

# Example usage
data = {'new_column_name': [1, 2, 3]}
df = CustomDataFrame(data)

# Accessing the new column
print(df.new_column_name)

# Accessing the old column (will raise a deprecation warning)
print(df.old_column_name)