Before hosting a race or a server hosting a session, you can select the changes allowed. Also the mods can stablish what changes are allowed in a session in the rfm files.
Example 1 taken from the RFM file:
// Settings that are free to be changed regardless of fixed or parc ferme setup. This can be overridden by the
// player file. You must add the values of each setting that drivers are free to change:
// 1 = steering lock
// 2 = brake pressure
// 4 = starting fuel
// 8 = fuel strategy
// 16 = tire compound
// 32 = brake bias
// 64 = front wing
// 128 = engine settings (rev limit, boost, and engine braking)
// For example, the default free settings are: steering lock (1) + brake pressure (2) + fuel strategy (8) = 11.
// Possible values are -1 (use default value) up to 255 (which equals 1+2+4+8+16+32+64+128).
FreeSettings = 255
Example 2 taken from the PLR file:
QUICK ParcFerme="3" // 0=off, 1=no setup changes allowed between qual and race except for 'Free Settings'), 2=same unless rain, 3=use RFM default 'ParcFerme=<0-2>'
MULTI ParcFerme="3" // 0=off, 1=no setup changes allowed between qual and race except for 'Free Settings'), 2=same unless rain, 3=use RFM default 'ParcFerme=<0-2>'
Example 3 also in PLR file:
QUICK FreeSettings="-1" // -1=use RFM/season/GDB default, or add to allow minor changes with fixed/parc ferme setups: 1=steering lock, 2=brake pressure, 4=starting fuel, 8=fuel strategy 16=tire compound, 32=brake bias, 64=front wing, 128=engine settings
MULTI FreeSettings="-1"
BEWARE, changes in RFM files could result in a Mistmatch Error with the following disconnection from the server for those players who does not have the same RFM file as the server.