The term ALTS refers to three different job titles: ELEVS (5 letters), HTS (3 letters), and HGTS (4 letters). ELEVS stands for Elevator Service Technician, which is a person who maintains and repairs elevators. HTS stands for Heating Technician, which is a person who installs and repairs heating systems. HGTS stands for High-Rise Glazing Technician, which is a person who installs and repairs glass in high-rise buildings.