Constant EXTENDED_FEATURES_C 

pub const EXTENDED_FEATURES_C: CpuidValue<0x7, 0x0, ECX, ExtendedFeatureFlagsC>;

Leaf/Function 0x7, ECX

[intel/vol2]: Table 3-8. Information Returned by CPUID Instruction. [amd/vol3]: E.3.6, CPUID Fn0000_0007_ECX_x0 Structured Extended Feature Identifiers (ECX=0).