API:KSPField
From Kerbal Space Program Wiki
KSPField is a C# annotation that may be applied to member variables of API:Parts, API:PartModules, etc to make their state persistent.
e.g.
class MyBlingModule : PartModule
{
[KSPField()]
protected double blingBrightness = 1000.0;
//...
}
adds a field that is exposed to ModuleManager, saved and restored by KSP on load and unload, etc.
