Below is a list of widely used Patch Lead/Cable Terminology and their definitions:

ANSI/TIA 568 C.2

Transmission Requirements

Return Loss

The loss of signal power as a result of signal reflection at a discontinuity in the cable.

Insertion Loss

The loss of signal power that results from devices inline.

Near End Crosstalk Loss (NEXT)

Loss caused by interference between two pairs in the cable, measured at the same end of the cable as the transmitter.

Power Sum Near-End Crosstalk Loss (PSNEXT)

Loss caused by the sum of near-end crosstalk of three pairs in the cable as they affect the fourth.

Far-End Crosstalk Loss (FEXT)

Loss caused by interference between two pairs in the cable, measured at the opposite end of the cable from the transmitter.

Attenuation Crosstalk Ratio Far-End (ACRF)

The difference between the signal attenuation and the far–end crosstalk, measured in decibels.

Power Sum Attenuation Crosstalk Ration Far-End (PSACRF)

The difference between the signal attenuation and the power sum far-end crosstalk, measured in decibels.

Transverse Conversion Loss (TCL)

The ratio of the measured common-mode voltage on a pair relative to a differential mode voltage applied on that same pair.

Equal Level Transverse Conversion Transfer Loss (ELTCTL)

The ratio of the measured common-mode voltage on a pair relative to a differential mode voltage on a different pair and normalized to be independent of length.

Coupling Attenuation

The ratio between the wanted signal power and the unwanted radiated power from the cabling.

Propagation Delay

The amount of time it takes for a signal to travel from the transmitter to the receiver over the cable.

Propagation Delay Skew

The difference in propagation delay between the fastest pair and the slowest pair.

Power Sum Alien Near-End Crosstalk Loss (PSANEXT)

Loss on one pair caused by the sum of alien crosstalk from other cables measured at the same end of the cable as the transmitter.

Average Power Sum Alien Near-End Crosstalk Loss (Average PSANEXT)

The average loss on all pairs caused by the sum of alien crosstalk from other cables, measured at the same end of the cable as the transmitter.

Power Sum Alien Far–End Crosstalk Loss (PSAFEXT)

Loss on one pair caused by the sum of alien crosstalk from other cables, measured at the opposite end of the cable from the transmitter.

Power Sum Alien Attenuation to Crosstalk Ratio Far-End (PSAACRF)

The difference between the signal attenuation and the power sum alien far-end crosstalk, measured in decibels.