An intermediate in the combustion of carbon and hydrocarbons, carbon monoxide, is of special importance because it is a poisonous gas, but also economically useful for the production of syngas. Solid and heavy liquid fuels also undergo a great number of pyrolysis reactions that give more easily oxidized, gaseous fuels.
GM is short for General Motors. in text means Good Morning or means Good Move. Also means Genetically Modified.
As an abbreviation, it could mean anything. Usually it's a small computer (personal digital assistant), and in that case I say handheld, no matter what actual type it is. I would just ask them. If you follow the links below you'll see they can be damm near anything.