F1 2019 Modding team.vtf.xml files

F1 2019 The Game (Codemasters)
I'm trying to disable R&D progression by modifying the upgrade values in each team's vtf file. This seems pretty straightforward, for the most part. For example, I've changed:
Code:
<Upgrade name="radUpgradeFrontDownforce">
    <F1Aero>
      <m_aero_front_cl_maxf_maxr value="1.1" op="*" />
      <m_aero_front_cl_maxf_minr value="1.1" op="*" />
      <m_aero_front_cl_minf_maxr value="1.1" op="*" />
      <m_aero_front_cl_minf_minr value="1.1" op="*" />
    </F1Aero>
  </Upgrade>

to:

Code:
<Upgrade name="radUpgradeFrontDownforce">
    <F1Aero>
      <m_aero_front_cl_maxf_maxr value="0" op="+" />
      <m_aero_front_cl_maxf_minr value="0" op="+" />
      <m_aero_front_cl_minf_maxr value="0" op="+" />
      <m_aero_front_cl_minf_minr value="0" op="+" />
    </F1Aero>
  </Upgrade>

However, I can't figure out what the very_low, medium, and very_high "upgrades" are (e.g., <Upgrade name="very_low">). Are those modifiers to R&D upgrade values, or do they relate to something like car setups? In other words, do I need to adjust the very_low/medium/very_high upgrades to ensure that teams don't make any performance progression in career mode?

Thanks for any help you can give me on this.
 
I tried to do the same in F1 2018. Turned off all upgrades, and in a race with fully upgraded cars ai had twice as much acceleration and top speed than me. It looks like the shutdown only affected me, not the bots. Through three races after file recovery the save was corrupted(9th season!, and even backups crashes in the same moment of season), so I don't recommend doing that.
 
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