Replacement Definitions are classified as Direct, Upgrade or Possible with different definitions for ICs and Discretes:

Direct (ICs) - Parts that are "fit, form, and function" replacements for the selected part. All key parameter values (the functionality parameters, package types, pinouts, power supply voltages, etc.) and all performance-type parameter values (the speed, gain, accuracy, etc.) are identical between the original part and the suggested replacements.

Direct (Discretes) - All compared electrical parameter values are identical between the original part and the suggested replacements.

Upgrade (ICs) - Parts that are "fit, form, and function" replacements for the selected part. All key parameter values (the functionality parameters, package types, pinouts, power supply voltages, etc.) are identical between the original part and the suggested upgrade replacements. At least one compared performance-type parameter value (the speed, gain, accuracy, etc.) is better than the original part and all other performance-type parameter values are identical or better than the original part.

Upgrade (Discretes) - At least one compared electrical parameter value is better than the original part and all other compared electrical parameter values are identical or better than the original part.

Possible (ICs) - Parts that are "fit, form, and function" replacements for the selected part. All key parameter values (the functionality parameters, package types, pinouts, power supply voltages, etc.) are the same as the original part. At least one compared performance-type parameter value (the speed, gain, accuracy, etc.) is worse than the original part.

Possible (Discretes) - At least one compared electrical parameter value is worse than the original part .