IOSSReader used to have a method ReadGlobalFields to control if the global fields would be reader or not. This method has been deprecated in favor of a more flexible approach using GlobalFields to allow users to select specific global fields to be read. This is particularly useful when dealing with datasets with a large number of global fields, as it allows users to read only the fields they are interested in, improving performance and reducing memory usage.

Additionally, IOSSReader can now control whether to group alphabetic vector field components, such as vel_x, vel_y, vel_z into a single vector field, such as vel, something which was automatically done before.

Finally, the IOSSReader's ReadAllFilesToDetermineStructure default value has been changed to false. This change improves performance on the common case, and the user will still be notified if the flag needs to be turned on.