WLAN Abstracted PHY Simulink Model

Hello

I am working on WLANMultiNodeAbstractedPHYModel simulink example in WLAN simulations. I need to know how can I modify the duration values, such as SIFS, ACKTX timeout and such. Can anyone help me on how to do that?

I can find the parameters as bus object, but I cannot find where they've been defined in the model.