Gunning Transceiver Logic or GTL is a type of logic signalling used to drive electronic backplane buses. It has a voltage swing between 0.4 volts and 1.2 volts, much lower than that used in TTL and CMOS logic, and symmetrical parallel resistive termination. The maximum signalling frequency is specified to be 100 MHz, although some applications use higher frequencies.

GTL is defined by JEDEC standard JESD 8-3 (1993).

The bus used in the Pentium Pro, Pentium II and Pentium III processors made by Intel uses GTL+ (or GTLP, developed by Fairchild Semiconductor), an upgraded version of GTL which has defined slew rates and higher voltage levels.

Gas to liquid or GTL is a refinery process to convert natural gas or other gaseous hydro-carbons into longer-chain hydro-carbons. Using such processes, refineries can convert some of their gaseous waste products into valuable fuel oils, which can be sold as or blended with Diesel fuel. This process will be increasingly significant as crude oil resources are depleted, while natural gas supplies are projected to last into the 22nd century.

GTL is an abbreviation for "Group Term Life". This is the tax Americans pay on employer-provided life insurance in excess of $50,000. The tax rate is set by the IRS based on the age of the taxpayer. (the older you are, more tax you have to pay for the same amount of company-provided life insurance). It's called Excess Life Insurance or EXLI in some payroll systems.

Reference

• Fairchild Semiconductor, Application Note AN-1070, GTLP vs. GTL: A Performance Comparsion from a System Perspective, 1997